Patent Publication Number: US-2022233083-A1

Title: Sphygmomanometer, blood pressure measurement method, and computer-readable recording medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation application of International Application No. PCT/JP2020/037769, with an International filing date of Oct. 5, 2020, which claims priority of Japanese Patent Application No. 2019-193674 filed on Oct. 24, 2019, the entire content of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a sphygmomanometer, and more particularly to a sphygmomanometer having a nocturnal (sleep) blood pressure measurement mode. The present invention also relates to a blood pressure measurement method for measuring blood pressure using such a sphygmomanometer. The present invention also relates to a computer-readable recording medium storing a program for causing a computer to execute such a blood pressure measurement method. 
     BACKGROUND ART 
     For example, Patent Document 1 (WO 2018/168797 A) has disclosed this type of sphygmomanometer. In the sphygmomanometer, in a nocturnal (sleep) blood pressure measurement mode, a blood pressure measurement period is specified, a measurement start time (or start clock time) and a measurement end time (or end clock time) are set, time setting is made with arbitrary time intervals (for example, one hour), and blood pressure is measured and recorded. 
     SUMMARY OF THE INVENTION 
     Incidentally, while using the sphygmomanometer in the nocturnal blood pressure measurement mode during sleep, for example, a subject sometimes temporarily gets up to go to a bathroom. Here, the conventional sphygmomanometer may start blood pressure measurement scheduled in advance (by a built-in timer) while the subject is out of bed and moving. As is known, blood pressure measured while the subject is moving will be higher than that measured at rest. Hence, in the conventional sphygmomanometer, there is a possibility of measuring blood pressure incorrectly in the nocturnal blood pressure measurement mode. 
     Thus, an object of the present invention is to provide a sphygmomanometer and a blood pressure measurement method capable of preventing the start of blood pressure measurement scheduled in advance in the nocturnal blood pressure measurement mode while a subject is temporarily out of bed. Another object of the present invention is to provide a computer-readable recording medium storing a program for causing a computer to execute such a blood pressure measurement method. 
     In order to solve the above-mentioned problem, a sphygmomanometer of the present disclosure that performs blood pressure measurement by temporarily compressing a measurement site of a subject with a blood pressure measurement cuff, 
     the sphygmomanometer having a nocturnal blood pressure measurement mode in which blood pressure measurement automatically starts according to a schedule determined in advance, 
     the sphygmomanometer comprising: 
     a blood pressure measurement unit configured to automatically start blood pressure measurement according to the schedule and measure blood pressure when the blood pressure measurement cuff is in a pressurization process or a depressurization process, in the nocturnal blood pressure measurement mode; 
     a single operation switch for inputting an instruction to suspend the nocturnal blood pressure measurement mode or to recover to the nocturnal blood pressure measurement mode; 
     a suspension processing unit configured to perform a process for transitioning to a measurement suspension state in which blood pressure measurement does not start even when a clock time set in the schedule arrives, when the single operation switch is operated at a first time, in the nocturnal blood pressure measurement mode; and 
     a recovery processing unit configured to perform a process for recovering to the nocturnal blood pressure measurement mode, under condition that the single operation switch is operated at a second time or after a lapse of a predetermined time from a clock time when the single operation switch is operated at the first time, in the measurement suspension state. 
     Here, the “predetermined time” is set to five minutes, for example, assuming a time required for the subject to get up from a bed, use a bathroom, and return to the bed again. However, the present disclosure is not limited to this. 
     In another aspect, a blood pressure measurement method of the present disclosure for a sphygmomanometer that performs blood pressure measurement by temporarily compressing a measurement site of a subject with a blood pressure measurement cuff, 
     the sphygmomanometer 
     having a nocturnal blood pressure measurement mode in which blood pressure measurement automatically starts according to a schedule determined in advance, and 
     including a single operation switch for inputting an instruction to suspend the nocturnal blood pressure measurement mode or to recover to the nocturnal blood pressure measurement mode, 
     the blood pressure measurement method comprising: 
     automatically starting blood pressure measurement according to the schedule and measuring blood pressure when the blood pressure measurement cuff is in a pressurization process or a depressurization process, in the nocturnal blood pressure measurement mode; 
     performing a process for transitioning to a measurement suspension state in which blood pressure measurement does not start even when a clock time set in the schedule arrives, when the single operation switch is operated at a first time, in the nocturnal blood pressure measurement mode; and 
     performing a process for recovering to the nocturnal blood pressure measurement mode, under condition that the single operation switch is operated at a second time or after a lapse of a predetermined time from a clock time when the single operation switch is operated at the first time, in the measurement suspension state. 
     In yet another aspect, a computer-readable recording medium of the present disclosure is a computer-readable recording medium non-transitorily storing a program for causing a computer to execute the blood pressure measurement method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a view illustrating an appearance of a wrist-type sphygmomanometer according to an embodiment of the present invention. 
         FIG. 2  is a diagram illustrating a block configuration of the sphygmomanometer. 
         FIG. 3  is a view illustrating how the sphygmomanometer is worn on a left wrist as a measurement site. 
         FIG. 4A  is a view illustrating a sitting posture as a measurement posture. 
         FIG. 4B  is a view illustrating a supine posture as a measurement posture. 
         FIG. 5  is a flowchart illustrating an operation flow of blood pressure measurement in a normal blood pressure measurement mode performed by the sphygmomanometer. 
         FIG. 6A  is a flowchart illustrating an operation flow of blood pressure measurement in a case where, when the sphygmomanometer performs the blood pressure measurement in a nocturnal blood pressure measurement mode, a subject temporarily gets up and operates a measurement suspension switch at a first time and then operates the measurement suspension switch at a second time. 
         FIG. 6B  is a flowchart illustrating an operation flow of a measurement suspension switch process in the operation flow of the blood pressure measurement of  FIG. 6A . 
         FIG. 6C  is a flowchart illustrating an operation flow of a blood pressure measurement process in the operation flow of the blood pressure measurement. 
         FIG. 6D  is a diagram illustrating, with elapsed time, a relationship between operation timings of a nocturnal measurement switch and the measurement suspension switch and a measurement schedule of the nocturnal blood pressure measurement mode in the blood pressure measurement of  FIG. 6A . 
         FIG. 6E  is a diagram illustrating measurement results of the blood pressure measurement performed by the sphygmomanometer. 
         FIG. 7A  is a flowchart illustrating an operation flow of blood pressure measurement in a case where, when the sphygmomanometer performs the blood pressure measurement in the nocturnal blood pressure measurement mode, a subject temporarily gets up and operates the measurement suspension switch at a first time, and the sphygmomanometer recovers to the nocturnal blood pressure measurement mode after a lapse of a predetermined time from a clock time when the subject operates the measurement suspension switch at a second time. 
         FIG. 7B  is a flowchart illustrating an operation flow of a measurement suspension switch process in the operation flow of the blood pressure measurement of  FIG. 7A . 
         FIG. 7C  is a flowchart illustrating an operation flow of a measurement suspension post-recovery timer process in the operation flow of the blood pressure measurement of  FIG. 7A . 
         FIG. 7D  is a diagram illustrating, with elapsed time, a relationship between operation timings of the nocturnal measurement switch and the measurement suspension switch and a measurement schedule of the nocturnal blood pressure measurement mode in the blood pressure measurement of  FIG. 7A . 
         FIG. 8A  is a flowchart illustrating an operation flow of blood pressure measurement in a case where, when the sphygmomanometer performs the blood pressure measurement in the nocturnal blood pressure measurement mode, a subject temporarily gets up and operates the measurement suspension switch at a first time, and the sphygmomanometer recovers to the nocturnal blood pressure measurement mode after a lapse of a predetermined time from a clock time when the subject operates the measurement suspension switch at the first time. 
         FIG. 8B  is a flowchart illustrating an operation flow of a measurement suspension switch process in the operation flow of the blood pressure measurement of  FIG. 8A . 
         FIG. 8C  is a flowchart illustrating an operation flow of a measurement suspension timer process in the operation flow of the blood pressure measurement of  FIG. 8A . 
         FIG. 8D  is a diagram illustrating, with elapsed time, a relationship between operation timings of the nocturnal measurement switch and the measurement suspension switch and a measurement schedule of the nocturnal blood pressure measurement mode in the blood pressure measurement of  FIG. 8A . 
     
    
    
     DESCRIPTION OF EMBODIMENTSMODES 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 
     Configuration of Sphygmomanometer 
       FIG. 1  illustrates an appearance of a wrist-type sphygmomanometer  100  according to an embodiment of the present invention. The sphygmomanometer  100  roughly includes a blood pressure measurement cuff  20  to be worn on a left wrist  90  as a measurement site (see  FIG. 3  described later) and a main body  10  integrally attached to the cuff  20 . 
     The cuff  20  is commonly used for a wrist-type sphygmomanometer, and has an elongated band shape so as to surround the left wrist  90  along a circumferential direction. The cuff  20  internally includes a fluid bag  22  (see  FIG. 2 ) for compressing the left wrist  90 . In order to always maintain the cuff  20  in an annular shape, the cuff  20  may internally include an appropriately flexible curler. 
     As illustrated in  FIG. 3 , the main body  10  is integrally attached to the band-shaped cuff  20  at a substantially central portion in a longitudinal direction. In this example, the portion where the main body  10  is attached is supposed to meet a palm-side surface (surface on a palm side of a hand)  90   a  of the left wrist  90  in a worn state. 
     The main body  10  has a flat substantially rectangular parallelepiped shape along an outer peripheral surface of the cuff  20 . The main body  10  is small and thin so as not to disturb sleep of a user (in this example, referring to a subject, and the same applies hereinafter). The main body  10  has rounded corner portions (the corners are rounded). 
     As illustrated in  FIG. 1 , the main body  10  has a surface (top surface) on a side farthest from the left wrist  90  among outer surfaces. The top surface is provided with a display  50  as a display screen and an operation unit  52  for inputting an instruction from the user. 
     In this example, the display  50  is constituted by a liquid crystal display (LCD) and displays given information according to control signals from a central processing unit (CPU)  110  to be described later. In this example, a highest blood pressure (unit; mmHg), a lowest blood pressure (unit; mmHg), and a pulse (unit; beats/min) are displayed. The display  50  may be constituted by an organic electro luminescence (EL) display or may include light emitting diodes (LEDs). 
     The operation unit  52  inputs an operation signal corresponding to an instruction from the user to the CPU  110  to be described later. In this example, the operation unit  52  includes a measurement switch  52 A, a nocturnal measurement switch  52 B, a measurement suspension switch  52 C, and a check switch  52 D. The measurement switch  52 A is provided for receiving a blood pressure measurement instruction from a user. The nocturnal measurement switch  52 B is provided for receiving an instruction to switch between a normal blood pressure measurement mode and a nocturnal blood pressure measurement mode. The measurement suspension switch  52 C is provided as a single operation switch for inputting an instruction to suspend the nocturnal blood pressure measurement mode or to recover to the nocturnal blood pressure measurement mode. The check switch  52 D is provided for displaying a stored measurement result on the display unit  50 . Here, the “normal blood pressure measurement mode” means a mode in which, when a blood pressure measurement instruction is input through the measurement switch  52 A, blood pressure measurement is performed in response to the blood pressure measurement instruction. The “nocturnal blood pressure measurement mode” means a mode in which blood pressure measurement automatically starts according to a schedule determined in advance so that blood pressure values can be measured while the user is sleeping. The schedule determined in advance indicates a plan of measurement set at fixed clock times such as 1:00 AM, 2:00 AM, and 3:00 AM, a plan of measurement set at, for example, two-hour intervals after the nocturnal measurement switch  52 B is pressed, and the like. 
     Specifically, in this example, each of the measurement switch  52 A, the nocturnal measurement switch  52 B, and the measurement suspension switch  52 C is a momentary (self-restoring) switch, and is in an on state only while being pressed down and is restored to an off state when being released. 
     When the sphygmomanometer  100  is in the normal blood pressure measurement mode, pressing down the measurement switch  52 A at a first time, which means a blood pressure measurement instruction, causes the cuff  20  to temporarily compress the measurement site (left wrist  90 ) for execution of blood pressure measurement by an oscillometric method. Pressing down the measurement switch  52 A at a second time during the blood pressure measurement (for example, during pressurization of the cuff  20 ), which means an instruction to stop the blood pressure measurement, causes immediate stop of the blood pressure measurement. 
     When the sphygmomanometer  100  is in the normal blood pressure measurement mode, pressing down the nocturnal measurement switch  52 B at a first time, which means an instruction to transition to the nocturnal blood pressure measurement mode, causes the sphygmomanometer  100  to transition from the normal blood pressure measurement mode to the nocturnal blood pressure measurement mode. In the nocturnal blood pressure measurement mode, as described above, blood pressure measurement by the oscillometric method automatically starts according to the schedule determined in advance. When the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode, pressing down the nocturnal measurement switch  52 B at a second time, which means an instruction to stop the nocturnal blood pressure measurement mode, causes the sphygmomanometer  100  to transition from the nocturnal blood pressure measurement mode to the normal blood pressure measurement mode. 
     In this example, an indicator lamp  54  is provided integrally with the nocturnal measurement switch  52 B. The indicator lamp  54  is turned off while the sphygmomanometer  100  is in the normal blood pressure measurement mode. On the other hand, the indicator lamp  54  is turned on while the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode. The indicator lamp  54  is temporarily turned off only while the sphygmomanometer is in a measurement suspension state to be described later. This allows the subject to check whether the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode or in the measurement suspension state by viewing the indicator lamp  54 . 
     Even when the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode, the user may press the measurement switch  52 A to provide an interrupting blood pressure measurement instruction separately from the schedule determined in advance. At that time, in response to the interrupting blood pressure measurement instruction, the cuff  20  temporarily compresses the measurement site (left wrist  90 ) for execution of blood pressure measurement by the oscillometric method. 
       FIG. 2  illustrates a block configuration of the sphygmomanometer  100 . 
     As described above, the cuff  20  includes the fluid bag  22  for compressing the left wrist  90  as the measurement site. The fluid bag  22  is connected to the main body  10  by an air pipe  39  for a fluid to be able to flow. 
     The main body  10  is equipped with, in addition to the display  50  and the operation unit  52  described above, the CPU  110  as a control unit, a memory  51  as a storage unit, a power supply unit  53 , a pressure sensor  31 , a pump  32 , and a valve  33 . The main body  10  is further equipped with an A/D conversion circuit  310  that converts output of the pressure sensor  31  from an analog signal to a digital signal, a pump drive circuit  320  that drives the pump  32 , and a valve drive circuit  330  that drives the valve  33 . The pressure sensor  31 , the pump  32 , and the valve  33  are connected to the fluid bag  22  through the air pipe  39  in common for a fluid to be able to flow. 
     The memory  51  stores a program for controlling the sphygmomanometer  100 , data used for controlling the sphygmomanometer  100 , setting data for setting various functions of the sphygmomanometer  100 , measurement result data of blood pressure values, and the like. The memory  51  is also used as a work memory when the program is executed or the like. Particularly, in this example, the memory  51  stores an algorithm for blood pressure calculation by the oscillometric method. 
     The CPU  110  shown in  FIG. 2  controls the entire operation of the sphygmomanometer  100 . Specifically, the CPU  110  works as a blood pressure measurement unit, and controls driving of the pump  32  and the valve  33  in response to operation signals from the operation unit  52  according to the program for controlling the sphygmomanometer  100  stored in the memory  51 . The CPU  110  works as the blood pressure measurement unit, and in the nocturnal blood pressure measurement mode, automatically starts blood pressure measurement according to the schedule and measures blood pressure using the algorithm for blood pressure calculation by the oscillometric method when the blood pressure measurement cuff is in a pressurization process or a depressurization process. The CPU  110  also works as a suspension processing unit, and performs a process for transitioning to the measurement suspension state in which blood pressure measurement does not start even when a clock time set in the schedule arrives, when the measurement suspension switch  52 C is turned on at a first time. The CPU  110  also works as a recovery processing unit, and in the measurement suspension state, performs a process for recovering to the nocturnal blood pressure measurement mode, under condition that the measurement suspension switch  52 C is turned on at a second time or after a lapse of a predetermined time from a clock time when the measurement suspension switch  52 C is turned on at the first time. These processes will be described in detail later. 
     In this example, the power supply unit  53  is constituted by a secondary battery, and supplies power to each of the CPU  110 , the pressure sensor  31 , the pump  32 , the valve  33 , the display  50 , the memory  51 , the A/D conversion circuit  310 , the pump drive circuit  320 , and the valve drive circuit  330 . 
     The pump  32  supplies air as the fluid into the fluid bag  22  through the air pipe  39  to increase pressure (cuff pressure) in the fluid bag  22  included in the cuff  20 . The valve  33  is opened and closed to control the cuff pressure by releasing or trapping the air in the fluid bag  22  through the air pipe  39 . The pump drive circuit  320  drives the pump  32  based on a control signal from the CPU  110 . The valve drive circuit  330  opens and closes the valve  33  based on a control signal from the CPU  110 . 
     The pressure sensor  31  and the A/D conversion circuit  310  work as a pressure detection unit that detects the pressure of the cuff. In this example, the pressure sensor  31  is a piezoresistive pressure sensor, and outputs the pressure (cuff pressure) in the fluid bag  22  included in the cuff  20  as an electrical resistance due to a piezoresistive effect through the air pipe  39 . The A/D conversion circuit  310  converts the output (electrical resistance) of the pressure sensor  31  from an analog signal to a digital signal and outputs the converted signal to the CPU  110 . In this example, the A/D conversion circuit  310  works as an oscillation circuit that oscillates at a frequency corresponding to the electrical resistance from the pressure sensor  31 . The CPU  110  acquires a signal indicating the cuff pressure based on the oscillation frequency. 
     Blood Pressure Calculation Method 
       FIG. 5  illustrates an operation flow when a user uses the sphygmomanometer  100  to perform blood pressure measurement in the normal blood pressure measurement mode. In this example, pressing the measurement switch  52 A continuously for, for example, 3 seconds or more in a power-off state causes the sphygmomanometer to be powered on in the normal blood pressure measurement mode by default. 
     As illustrated in  FIG. 4A , it is assumed that a user  80  wearing the sphygmomanometer  100  on the left wrist  90  is in a sitting posture. 
     Here, as illustrated in  FIG. 4A , the “sitting posture” means a posture in which the user  80  wearing the sphygmomanometer  100  on the left wrist  90  sits on a chair  97  or the like, and holds the left wrist  90  (and the sphygmomanometer  100 ) at a height level of a heart  81  by raising the left wrist  90  obliquely (hand up, elbow down) in front of a trunk with a left elbow on a table  98 . On the other hand, as illustrated in  FIG. 4B , a “supine posture” means a posture in which the user  80  wearing the sphygmomanometer  100  on the left wrist  90  lies on his/her back on a horizontal floor  99  or the like with the left elbow extended along the trunk. 
     As shown in step S 1  in  FIG. 5 , when the user presses down the measurement switch  52 A provided on the main body  10  to input a blood pressure measurement instruction, the CPU  110  initializes the pressure sensor  31  (step S 2 ). Specifically, the CPU  110  initializes a processing memory area and performs 0 mmHg adjustment (sets an atmospheric pressure to 0 mmHg) on the pressure sensor  31  with the pump  32  off (stopped) and the valve  33  open. 
     Next, the CPU  110  closes the valve  33  via the valve drive circuit  330  (step S 3 ), and then turns on (activates) the pump  32  via the pump drive circuit  320  to start pressurization of the cuff  20  (fluid bag  22 ) (step S 4 ). At this time, the CPU  110  controls an increase rate of a cuff pressure PC, which is the pressure in the fluid bag  22 , based on the output of the pressure sensor  31  while supplying air from the pump  32  to the fluid bag  22  through the air pipe  39 . 
     Next, in step S 5  in  FIG. 5 , the CPU  110  works as a pressure measurement unit, and determines whether a predetermined pressure is reached. When the predetermined pressure is reached (Yes in step S 5 ), a wrapping state of the cuff  20  is determined and displayed (step S 6 ). The wrapping state can be determined by a publicly known technique as disclosed in, for example, the specification of Japanese Patent No. 5408142. On the other hand, when the predetermined pressure is not reached (No in step S 5 ), the pressurization of the cuff  20  is continued. 
     Next, in step S 7  in  FIG. 5 , calculation of blood pressure values (highest blood pressure (systolic blood pressure) and lowest blood pressure (diastolic blood pressure)) is attempted using the algorithm for blood pressure calculation stored in the memory  51  based on currently acquired pulse wave signals (fluctuation components due to the pulse wave included in the output of the pressure sensor  31 ). 
     When the blood pressure values cannot be calculated yet at this point due to lack of data (No in step S 8 ), the processing of steps S 4  to S 8  is repeated until the cuff pressure PC reaches an upper limit pressure (for example, set in advance to 300 mmHg for safety). 
     When the blood pressure values can be calculated in this manner (Yes in step S 8 ), the CPU  110  turns off the pump  32  (step S 9 ) and opens the valve  33  (step S 10 ) to control the release of the air in the cuff  20  (fluid bag  22 ). 
     Thereafter, the CPU  110  displays the calculated blood pressure values on the display  50  (step S 11 ), and controls storing of the blood pressure values in the memory  51 . 
     First Embodiment 
       FIG. 6A  illustrates an operation flow of blood pressure measurement in a case where, when using the sphygmomanometer  100  to perform the blood pressure measurement in the nocturnal blood pressure measurement mode, a user temporarily gets up, for example, to go to a bathroom and turns on the measurement suspension switch  52 C at a first time and then turns on the measurement suspension switch  52 C at a second time. Here, it is assumed that the user  80  wearing the sphygmomanometer  100  on the left wrist  90  is in the supine posture as illustrated in  FIG. 4B . 
     As shown in step S 21  in  FIG. 6A , when the user presses down the nocturnal measurement switch  52 B provided on the main body  10 , the sphygmomanometer  100  transitions from the normal blood pressure measurement mode to the nocturnal blood pressure measurement mode. At this time, the indicator lamp  54  (see  FIG. 1 ) is turned on in the sphygmomanometer  100 . This allows the user to check that the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode by viewing the indicator lamp  54 . In this example, as illustrated in  FIG. 6D , it is assumed that the nocturnal measurement switch  52 B is pressed at 11:30 PM for transition to the nocturnal blood pressure measurement mode. It is also assumed that there is determined a schedule in which, for example, measurement is set at a fixed clock time of 2:00 AM and at 3:30 AM, that is 4 hours after a clock time when the nocturnal measurement switch  52 B is pressed (note that, in  FIG. 6D  and  FIGS. 7D and 8D  described later, time is shown in 24-hour notation, such as 23:30). 
     As shown in step S 22  in  FIG. 6A , the CPU  110  determines whether the user has pressed down the measurement suspension switch  52 C provided on the main body  10 . When the user has pressed down the measurement suspension switch  52 C provided on the main body  10  (Yes in step S 22 ), the CPU  110  works as the suspension processing unit for transition to a measurement suspension switch process (step S 23 ). At this time, the indicator lamp  54  is turned off in the sphygmomanometer  100 . This allows the user to check that the sphygmomanometer  100  is in the measurement suspension state by viewing the indicator lamp  54 . In this example, as illustrated in  FIG. 6D , it is assumed that the user presses down the measurement suspension switch  52 C at 1:57 AM. 
     As shown in step S 31  in  FIG. 6B , in the measurement suspension switch process, the CPU  110  determines whether the sphygmomanometer  100  is in the measurement suspension state. When the sphygmomanometer  100  is not in the measurement suspension state (No in step S 31 ), the CPU  110  works as the suspension processing unit and sets the measurement suspension state (step S 32 ). In this example, the CPU  110  sets a suspension flag in the memory  51 . Thereafter, the measurement suspension switch process is ended, and the processing returns to step S 24  in  FIG. 6A . 
     As shown in step S 24  in  FIG. 6A , the CPU determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode. When it is not a measurement clock time according to the schedule (No in step S 24 ), the processing returns to step S 22 , and the CPU determines whether the user has pressed down the measurement suspension switch  52 C. When the user has not pressed down the measurement suspension switch  52 C (No in step S 22 ), the sphygmomanometer  100  waits for a measurement clock time according to the schedule. 
     As shown in step S 24  in  FIG. 6A , the CPU  110  determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode. When it is a measurement clock time according to the schedule (Yes in step S 24 ), the CPU  110  subsequently determines whether the measurement suspension state has been set. When the measurement suspension state has been set (Yes in step S 25 ), the sphygmomanometer  100  cancels a blood pressure measurement process (step S 26 ). In this example, as illustrated in  FIG. 6D , the measurement set at 2:00 AM in the schedule is canceled. 
     As shown in step S 27  in  FIG. 6A , the CPU  110  determines whether the measurement set in the schedule of the nocturnal blood pressure measurement mode has been completed. When the given measurement has not been completed (incomplete in step S 27 ), the processing returns to step S 22 . 
     As shown in step S 22  in  FIG. 6A , during standby, the CPU  110  determines whether the user has pressed down the measurement suspension switch  52 C provided on the main body  10 . When the user has pressed down the measurement suspension switch  52 C at a second time, for example, after going to the bathroom (Yes in step S 22 ), the sphygmomanometer  100  transitions to the measurement suspension switch process (step S 23 ). In this example, as illustrated in  FIG. 6D , it is assumed that the user presses down the measurement suspension switch  52 C at 2:03 AM. 
     As shown in step S 31  in  FIG. 6B , in the measurement suspension switch process, the CPU  110  determines whether the sphygmomanometer  100  is in the measurement suspension state. When the sphygmomanometer  100  is in the measurement suspension state (Yes in step S 31 ), the CPU  110  works as the recovery processing unit and resets the measurement suspension state for recovery from the measurement suspension state (step S 33 ). Thereafter, the measurement suspension switch process is ended, and the sphygmomanometer  100  recovers to the nocturnal blood pressure measurement mode. In this example, the sphygmomanometer  100  turns on the indicator lamp  54  to indicate that the measurement suspension switch  52 C has been turned on at the second time. This allows the user to easily check the recovery to the nocturnal blood pressure measurement mode. 
     As shown in step S 24  in  FIG. 6A , the CPU  110  determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode. When it is a measurement clock time according to the schedule (Yes in step S 24 ), the CPU  110  subsequently determines whether the measurement suspension state has been set. When the measurement suspension state has been reset (No in step S 25 ), the sphygmomanometer  100  proceeds to the blood pressure measurement process (step S 26 ). In this example, as illustrated in  FIG. 6D , the measurement set at 3:30 AM in the schedule is performed. 
     In the blood pressure measurement process shown in step S 26  in  FIG. 6A , the CPU  110  works as the blood pressure measurement unit and measures blood pressure. As illustrated in  FIG. 6C , the blood pressure measurement process is performed according to steps similar to steps S 2  to S 11  excluding steps S 5  and S 6  in  FIG. 5  described above. As shown in step S 27  in  FIG. 6A , the CPU  110  subsequently determines whether the measurement set in the schedule of the nocturnal blood pressure measurement mode has been completed. When all the given measurement has been completed (complete in step S 27 ), the nocturnal blood pressure measurement mode of the sphygmomanometer  100  is ended. At this time, the indicator lamp  54  is turned off. 
     Therefore, according to the sphygmomanometer  100 , it is possible to prevent the start of blood pressure measurement scheduled in advance in the nocturnal blood pressure measurement mode while the subject is temporarily out of bed. 
     In this example, as illustrated in  FIG. 6E , the sphygmomanometer  100  stores measurement results in the memory  51  as follows. At 2:00 AM on Sep. 1, 2019, the highest blood pressure (systolic blood pressure (SYS))=102 mmHg, the lowest blood pressure (diastolic blood pressure (DIA))=78 mmHg, and the pulse (PLS)=56 times/min were stored. At 3:30 AM on the same day, the systolic blood pressure (SYS)=98 mmHg, the diastolic blood pressure (DIA)=68 mmHg, and the pulse (PLS)=48 times/min were stored. Next, at 1:57 AM on the next day, September 2, the user pressed down the measurement suspension switch  52 C during measurement in the nocturnal blood pressure measurement mode. As a result, the measurement set in advance at 2:00 AM in the schedule was canceled, and the blood pressure measurement was not executed. At 2:03 AM, the user pressed down the measurement suspension switch  52 C, and thus the sphygmomanometer recovered to be in the nocturnal blood pressure measurement mode thereafter. Then, at 3:34 AM, that is 4 hours after a clock time when the nocturnal measurement switch  52 B was pressed, the highest blood pressure (systolic blood pressure (SYS))=97 mmHg, the lowest blood pressure (diastolic blood pressure (DIA))=68 mmHg, and the pulse (PLS)=49 times/min were stored. Next, at 2:00 AM on the next day, September 3, no measurement result was stored because the sphygmomanometer  100  had an operation error due to body motion of the subject. At 3:14 AM, that is 4 hours after a clock time when the nocturnal measurement switch  52 B was pressed, on the same day, September 3, the highest blood pressure (systolic blood pressure (SYS))=90 mmHg, the lowest blood pressure (diastolic blood pressure (DIA))=61 mmHg, and the pulse (PLS)=45 times/min were stored. 
     Second Embodiment 
       FIG. 7A  illustrates an operation flow of blood pressure measurement in a case where, when using the sphygmomanometer  100  to perform the blood pressure measurement in the nocturnal blood pressure measurement mode, a user temporarily gets up and turns on the measurement suspension switch  52 C at a first time, and the sphygmomanometer  100  recovers to the nocturnal blood pressure measurement mode after a lapse of a predetermined time from a clock time when the measurement suspension switch  52 C is turned on at a second time. In this example, as illustrated in  FIG. 7D , it is assumed that the nocturnal measurement switch  52 B is pressed at 11:30 PM for transition to the nocturnal blood pressure measurement mode. It is also assumed that there is determined a schedule in which, for example, measurement is set at a fixed clock time of 2:00 AM and at 3:30 AM, that is 4 hours after a clock time when the nocturnal measurement switch  52 B is pressed. In this example, the user presses down the measurement suspension switch  52 C at the first time at 3:24 AM, and then presses down the measurement suspension switch  52 C at the second time at 3:29 AM. Subsequently, the sphygmomanometer  100  automatically recovers to the nocturnal blood pressure measurement mode at 3:34 AM, that is after a lapse of a predetermined time Ta (in this example, five minutes). 
     As shown in step S 51  in  FIG. 7A , when the user presses down the nocturnal measurement switch  52 B provided on the main body  10 , the sphygmomanometer  100  transitions from the normal blood pressure measurement mode to the nocturnal blood pressure measurement mode. At this time, the indicator lamp  54  is turned on in the sphygmomanometer  100 . 
     As shown in step S 52  in  FIG. 7A , the CPU  110  determines whether the user has pressed down the measurement suspension switch  52 C provided on the main body  10 . When the user has pressed down the measurement suspension switch  52 C provided on the main body  10  (Yes in step S 52 ), the sphygmomanometer  100  transitions to a measurement suspension switch process (step S 53 ). 
     As shown in step S 61  in  FIG. 7B , in the measurement suspension switch process, the CPU  110  determines whether the sphygmomanometer  100  is in the measurement suspension state. When the sphygmomanometer  100  is not in the measurement suspension state (No in step S 61 ), the CPU  110  works as the suspension processing unit and sets the measurement suspension state (step S 62 ). At this time, the indicator lamp  54  is turned off. Subsequently, the CPU  110  turns off a measurement suspension post-recovery timer (step S 63 ). Thereafter, the measurement suspension switch process is ended, and the processing returns to step S 54  in  FIG. 7A . 
     As shown in step S 54  in  FIG. 7A , the CPU  110  determines whether the measurement suspension post-recovery timer of the sphygmomanometer  100  is on. When the measurement suspension post-recovery timer is not on (No in step S 54 ), the CPU determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode (step S 56 ). When it is not a measurement clock time according to the schedule (No in step S 56 ), the processing returns to step S 52 , and it is determined whether the user has pressed down the measurement suspension switch  52 C. When the user has not pressed down the measurement suspension switch  52 C (No in step S 52 ), the sphygmomanometer  100  waits for a measurement clock time according to the schedule. 
     As shown in step S 52  in  FIG. 7A , during standby, the CPU  110  determines whether the user has pressed down the measurement suspension switch  52 C provided on the main body  10 . When the user has presses down the measurement suspension switch  52 C provided on the main body  10  at the second time (Yes in step S 52 ), the sphygmomanometer  100  transitions to the measurement suspension switch process (step S 53 ). In this example, as illustrated in  FIG. 7D , it is assumed that the user presses down the measurement suspension switch  52 C at the second time at 3:29 AM. 
     As shown in step S 61  in  FIG. 7B , in the measurement suspension switch process, the CPU  110  determines whether the sphygmomanometer  100  is in the measurement suspension state. When the sphygmomanometer  100  is in the measurement suspension state (Yes in step S 61 ), the CPU determines whether the measurement suspension post-recovery timer is on. When the measurement suspension post-recovery timer is not on (No in step S 64 ), the CPU  110  works as the recovery processing unit and initializes the measurement suspension post-recovery timer (step S 65 ). Subsequently, the CPU  110  works as the recovery processing unit and turns on the measurement suspension post-recovery timer (step S 66 ). Thereafter, the measurement suspension switch process is ended, and the processing returns to step S 54  in  FIG. 7A . 
     As shown in step S 54  in  FIG. 7A , the CPU  110  determines whether the measurement suspension post-recovery timer of the sphygmomanometer  100  is on. When the measurement suspension post-recovery timer is on (Yes in step S 54 ), the sphygmomanometer  100  transitions to a measurement suspension post-recovery timer process (step S 55 ). 
     As shown in step S 71  in  FIG. 7C , in the measurement suspension post-recovery timer process, the CPU  110  works as the recovery processing unit and causes the measurement suspension post-recovery timer to count up. Subsequently, the CPU  110  works as the recovery processing unit and determines whether the predetermined measurement suspension post-recovery time Ta has elapsed (step S 72 ). When the predetermined measurement suspension recovery time Ta has not elapsed (No in step S 72 ), the measurement suspension post-recovery timer process is ended, and the processing returns to step S 56  in  FIG. 7A . In this example, the predetermined time Ta is set to five minutes, for example, assuming a time required for the user to enter a resting state after pressing the measurement suspension switch  52 C at the second time. However, the present disclosure is not limited to this. 
     In a case where the predetermined measurement suspension recovery time Ta has elapsed, as shown in step S 72  in  FIG. 7C , the CPU  110  works as the recovery processing unit and determines whether the predetermined measurement suspension post-recovery time Ta has elapsed. When determining that the predetermined measurement suspension recovery time Ta has elapsed (Yes in step S 72 ), the CPU  110  resets the measurement suspension state for recovery from the measurement suspension state (step S 73 ). Thereafter, the measurement suspension post-recovery timer process is ended, and the processing returns to step S 56  in  FIG. 7A . 
     As shown in step S 56  in  FIG. 7A , the CPU  110  determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode. When it is a measurement clock time according to the schedule (Yes in step S 56 ), the CPU  110  subsequently determines whether the measurement suspension state has been set. When the measurement suspension state has been set (Yes in step S 57 ), the sphygmomanometer  100  cancels a blood pressure measurement process (step S 58 ). In this example, as illustrated in  FIG. 7D , the measurement set at 3:30 AM is canceled. 
     In a case where the measurement suspension state has been reset, as shown in step S 57  in  FIG. 7A , the CPU  110  determines whether the measurement suspension state has been set. When it is determined that the measurement suspension state has been reset (No in step S 57 ), the sphygmomanometer  100  proceeds to the blood pressure measurement process (step S 58 ). In the blood pressure measurement process shown in step S 58 , the CPU  110  works as the blood pressure measurement unit and measures blood pressure. As illustrated in  FIG. 6C , the blood pressure measurement process is performed according to steps similar to steps S 2  to S 11  excluding steps S 5  and S 6  in  FIG. 5  described above. 
     As shown in step S 59  in  FIG. 7A , the CPU  110  determines whether the measurement set in the schedule of the nocturnal blood pressure measurement mode has been completed. When all the given measurement has been completed (Yes in step S 59 ), the nocturnal blood pressure measurement mode of the sphygmomanometer  100  is ended. 
     Thus, in the sphygmomanometer  100 , the process for recovering to the nocturnal blood pressure measurement mode is performed after a lapse of the predetermined time Ta from the clock time when the measurement suspension switch  52 C is turned on at the second time. As a result, it is possible to continue the nocturnal blood pressure measurement mode after waiting for the user to enter the resting state. 
     Third Embodiment 
       FIG. 8A  illustrates an operation flow of blood pressure measurement in a case where, when using the sphygmomanometer  100  to perform the blood pressure measurement in the nocturnal blood pressure measurement mode, a user temporarily gets up and turns on the operation switch at a first time, and the sphygmomanometer  100  recovers to the nocturnal blood pressure measurement mode after a lapse of a predetermined time from a clock time when the single operation switch is turned on at the first time. In this example, as illustrated in  FIG. 8D , it is assumed that the nocturnal measurement switch  52 B is pressed at 11:30 PM for transition to the nocturnal blood pressure measurement mode. It is also assumed that there is determined a schedule in which, for example, measurement is set at a fixed clock time of 2:00 AM and at 3:30 AM, that is 4 hours after a clock time when the nocturnal measurement switch  52 B is pressed. In this example, as illustrated in  FIG. 8D , it is assumed that the user presses down the measurement suspension switch  52 C at the first time at 1:57 AM. Then, the sphygmomanometer  100  automatically recovers to the nocturnal blood pressure measurement mode at 2:02 AM, that is after a lapse of a predetermined time Tb (in this example, five minutes). 
     As shown in step S 81  in  FIG. 8A , when the user presses down the nocturnal measurement switch  52 B provided on the main body  10 , the sphygmomanometer  100  transitions from the normal blood pressure measurement mode to the nocturnal blood pressure measurement mode. At this time, the indicator lamp  54  is turned on in the sphygmomanometer  100 . 
     As shown in step S 82  in  FIG. 8A , the CPU  110  determines whether the user has pressed down the measurement suspension switch  52 C provided on the main body  10 . When the user has pressed down the measurement suspension switch  52 C provided on the main body  10  (Yes in step S 82 ), the sphygmomanometer  100  transitions to a measurement suspension switch process (step S 83 ). In this example, it is assumed that the user presses down the measurement suspension switch  52 C at 1:57 AM. 
     As shown in step S 91  in  FIG. 8B , in the measurement suspension switch process, the CPU  110  determines whether the sphygmomanometer  100  is in the measurement suspension state. When the sphygmomanometer  100  is not in the measurement suspension state (No in step S 91 ), the CPU  110  works as the suspension processing unit and sets the measurement suspension state (step S 92 ). At this time, the indicator lamp  54  is turned off. Subsequently, the CPU  110  initializes a measurement suspension timer (step S 93 ). Subsequently, the CPU  110  turns on the measurement suspension timer (step S 94 ). Thereafter, the measurement suspension switch process is ended, and the processing returns to step S 84  in  FIG. 8A . 
     As shown in step S 84  in  FIG. 8A , the CPU  110  determines whether the measurement suspension timer of the sphygmomanometer  100  is on. When the measurement suspension timer is on (Yes in step S 84 ), the sphygmomanometer  100  transitions to a measurement suspension timer process (step S 85 ). 
     As shown in step S 101  in  FIG. 8C , in the measurement suspension timer process, the CPU  110  works as the recovery processing unit and causes the measurement suspension timer to count up. Subsequently, the CPU  110  determines whether the predetermined measurement post-suspension time Tb has elapsed (step S 102 ). When the predetermined measurement post-suspension time Tb has not elapsed (No in step S 102 ), the measurement suspension timer process is ended, and the processing returns to step S 86  in  FIG. 8A . In this example, the predetermined time Tb is set to five minutes, for example, assuming a time required for the user to get up from a bed, use a bathroom, and return to the bed again from a clock time when the user presses down the measurement suspension switch  52 C. However, the present disclosure is not limited to this. 
     As shown in step S 86  in  FIG. 8A , the CPU  110  determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode. When it is a measurement clock time according to the schedule (Yes in step S 86 ), the CPU  110  subsequently determines whether the measurement suspension state has been set. When the measurement suspension state has been set (Yes in step S 87 ), the sphygmomanometer  100  cancels a blood pressure measurement process (step S 88 ). In this example, as illustrated in  FIG. 8D , the measurement set at 2:00 AM is canceled. 
     As shown in step S 89  in  FIG. 8A , the CPU  110  determines whether the given measurement set in the schedule of the nocturnal blood pressure measurement mode has been completed. When the given measurement has not been completed (incomplete in step S 89 ), the processing returns to step S 82 . 
     As shown in step S 82  in  FIG. 8A , during standby, the CPU  110  determines whether the user has pressed down the measurement suspension switch  52 C provided on the main body  10 . The user is not required to press the measurement suspension switch  52 C even after going to the bathroom. When the measurement suspension switch  52 C has not been pressed down (No in step S 82 ), the CPU  110  subsequently determines whether the measurement suspension timer of the sphygmomanometer  100  is on. When the measurement suspension timer is on (Yes in step S 84 ), the sphygmomanometer  100  transitions to the measurement suspension timer process (step S 85 ). 
     As shown in step S 101  in  FIG. 8C , in the measurement suspension timer process, the CPU  110  works as the recovery processing unit and causes the measurement suspension timer to count up. Subsequently, the CPU  110  determines whether the predetermined measurement post-suspension time Tb has elapsed (step S 102 ). When the predetermined measurement suspension recovery time Tb has elapsed (Yes in step S 102 ), the CPU  110  works as the recovery processing unit and resets the measurement suspension state (step S 103 ). At this time, the indicator lamp  54  is turned on. Subsequently, the CPU  110  turns off the measurement suspension timer (step S 104 ). Thereafter, the measurement suspension timer process is ended, and the processing returns to step S 86  in  FIG. 8A . 
     Note that, in step S 82  in  FIG. 8A , when the user has pressed the measurement suspension switch  52 C after going to the bathroom (Yes in step S 82 ), as shown in step S 91  in  FIG. 8B , in the measurement suspension switch process, the CPU  110  determines whether the sphygmomanometer  100  is in the measurement suspension state. When the sphygmomanometer  100  is in the measurement suspension state (Yes in step S 91 ), the CPU  110  works as the recovery processing unit and resets the measurement suspension state (step S 95 ). At this time, the indicator lamp  54  is turned on. Subsequently, the CPU  110  turns off the measurement suspension timer (step S 96 ). 
     Thereafter, the measurement suspension switch process is ended, and the processing returns to step S 84  in  FIG. 8A . 
     As shown in step S 86  in  FIG. 8A , the CPU  110  determines whether it is a measurement clock time according to the schedule of the nocturnal blood pressure measurement mode. When it is a measurement clock time according to the schedule (Yes in step S 86 ), the CPU  110  subsequently determines whether the measurement suspension state has been set. When the measurement suspension state has been reset (No in step S 86 ), the sphygmomanometer  100  proceeds to the blood pressure measurement process (step S 88 ). In this example, as illustrated in  FIG. 8D , the measurement set at 3:30 AM in the schedule is performed. 
     As in the operation flow illustrated in  FIG. 6C , the blood pressure measurement process shown in step S 88  in  FIG. 8A  is performed according to steps similar to steps S 2  to S 11  excluding steps S 5  and S 6  in  FIG. 5  described above. As shown in step S 89  in  FIG. 8A , the CPU  110  subsequently determines whether the measurement set in the schedule of the nocturnal blood pressure measurement mode has been completed. When all the given measurement has been completed (complete in step S 89 ), the nocturnal blood pressure measurement mode of the sphygmomanometer  100  is ended. At this time, the indicator lamp  54  is turned off. 
     As is apparent from the above, according to the sphygmomanometer  100 , it is possible to prevent the start of blood pressure measurement scheduled in advance in the nocturnal blood pressure measurement mode while the subject is temporarily out of bed. 
     In addition, the indicator lamp  54  is turned on while the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode, and the indicator lamp  54  is temporarily turned off or blinking only while the sphygmomanometer  100  is in the measurement suspension state. Therefore, the user (subject) can check whether the sphygmomanometer  100  is in the nocturnal blood pressure measurement mode or in the measurement suspension state by viewing the indicator lamp  54 . 
     Modified Example 
     In each of the above-described examples, it is assumed that the nocturnal measurement switch  52 B is pressed at 11:30 PM for transition to the nocturnal blood pressure measurement mode, and in the schedule of the nocturnal blood pressure measurement mode, for example, measurement is set at a fixed clock time of 2:00 AM and at 3:30 AM, that is 4 hours after a clock time when the nocturnal measurement switch  52 B is pressed. However, the present disclosure is not limited to this schedule, and the schedule may be determined such that measurement is all set at fixed clock times such as 1:00 AM, 2:00 AM, and 3:00 AM between the clock time when the nocturnal measurement switch  52 B is pressed and 7:00 AM, for example. Alternatively, the schedule may be determined such that measurement is all set at relative clock times such as, 2 hours after, 3 hours after, and 4 hours after the clock time when the nocturnal measurement switch  52 B is pressed till 7:00 AM, for example. 
     In addition, since the sphygmomanometer  100  compresses a wrist (which is the left wrist  90  in the above examples, but may be a right wrist) as the measurement site, it is expected that the sphygmomanometer  100  hinders sleep of a user (subject) to a smaller extent than a sphygmomanometer that compresses an upper arm (Imai et al., “Development and evaluation of a home nocturnal blood pressure monitoring system using a wrist-cuff device”, Blood Pressure Monitoring 2018, 23, P318-326). Therefore, the sphygmomanometer  100  is suitable for nocturnal blood pressure measurement. 
     In addition, since the sphygmomanometer  100  is formed integrally and compactly as a wrist-type sphygmomanometer, it is handy for a user. 
     In the above embodiments, the sphygmomanometer  100  includes, as the operation unit  52 , the measurement switch  52 A, the nocturnal measurement switch  52 B, and the measurement suspension switch  52 C provided on the main body  10 , but the present disclosure is not limited thereto. The operation unit  52  may include, for example, a communication unit that receives an instruction via wireless communication from a smartphone or the like outside of the sphygmomanometer  100 . 
     In the above embodiments, the main body  10  is provided integrally with the cuff  20 , but the present disclosure is not limited thereto. The main body  10  may be formed as a separate body from the cuff  20 , and may be connected to the cuff  20  (fluid bag  22 ) via a flexible air tube for a fluid to be able to flow. 
     The above-described blood pressure measurement method may be recorded as software (computer program) on a recording medium capable of storing data in a non-transitory manner, such as a compact disc (CD), a digital versatile disc (DVD), or a flash memory. Installing the software recorded on such a recording medium in a substantial computer device such as a personal computer, a personal digital assistant (PDA), or a smartphone can cause the computer device to execute the above-described blood pressure measurement method. 
     As described above, a sphygmomanometer of the present disclosure that performs blood pressure measurement by temporarily compressing a measurement site of a subject with a blood pressure measurement cuff, 
     the sphygmomanometer having a nocturnal blood pressure measurement mode in which blood pressure measurement automatically starts according to a schedule determined in advance, the sphygmomanometer comprising: 
     a blood pressure measurement unit configured to automatically start blood pressure measurement according to the schedule and measure blood pressure when the blood pressure measurement cuff is in a pressurization process or a depressurization process, in the nocturnal blood pressure measurement mode; 
     a single operation switch for inputting an instruction to suspend the nocturnal blood pressure measurement mode or to recover to the nocturnal blood pressure measurement mode; 
     a suspension processing unit configured to perform a process for transitioning to a measurement suspension state in which blood pressure measurement does not start even when a clock time set in the schedule arrives, when the single operation switch is operated at a first time, in the nocturnal blood pressure measurement mode; and 
     a recovery processing unit configured to perform a process for recovering to the nocturnal blood pressure measurement mode, under condition that the single operation switch is operated at a second time or after a lapse of a predetermined time from a clock time when the single operation switch is operated at the first time, in the measurement suspension state. 
     Here, the “predetermined time” is set to five minutes, for example, assuming a time required for the subject to get up from a bed, use a bathroom, and return to the bed again. However, the present disclosure is not limited to this. 
     The sphygmomanometer of the present disclosure automatically starts blood pressure measurement according to the schedule in the nocturnal blood pressure measurement mode. The blood pressure measurement unit measures blood pressure when the blood pressure measurement cuff is in the pressurization process or the depressurization process. The instruction to suspend the nocturnal blood pressure measurement mode or to recover to the nocturnal blood pressure measurement mode is input to the single operation switch. The suspension processing unit performs the process for transitioning to the measurement suspension state in which blood pressure measurement does not start even when a clock time set in the schedule arrives, when the single operation switch is operated at the first time, in the nocturnal blood pressure measurement mode. The recovery processing unit performs the process for recovering to the nocturnal blood pressure measurement mode, under the condition that the single operation switch is operated at the second time or after a lapse of the predetermined time from the clock time when the single operation switch is operated at the first time, in the measurement suspension state. Therefore, according to the sphygmomanometer, it is possible to prevent the start of blood pressure measurement scheduled in advance in the nocturnal blood pressure measurement mode while the subject is temporarily out of bed. 
     In the sphygmomanometer of one embodiment, wherein the recovery processing unit is configured to, when complying with the condition that the single operation switch is operated at the second time, perform the process for recovering to the nocturnal blood pressure measurement mode immediately after the single operation switch is operated at the second time. 
     The sphygmomanometer of this embodiment can immediately recover to the nocturnal blood pressure measurement mode according to an instruction of the subject. 
     In the sphygmomanometer of one embodiment, wherein the recovery processing unit is configured to, when complying with the condition that the single operation switch is operated at the second time, perform the process for recovering to the nocturnal blood pressure measurement mode after a lapse of a predetermined time from a clock time when the single operation switch is operated at the second time. 
     Here, the “predetermined time” is set to five minutes, for example, assuming a time required for the subject to enter a resting state after pressing the single operation switch at the second time. However, the present disclosure is not limited to this. 
     In the sphygmomanometer of this embodiment, the process for recovering to the nocturnal blood pressure measurement mode is performed after a lapse of the predetermined time from the clock time when the single operation switch is operated at the second time. Therefore, it is possible to continue the nocturnal blood pressure measurement mode after waiting for the subject to enter the resting state. 
     In the sphygmomanometer of one embodiment, this sphygmomanometer comprises 
     an indicator lamp indicating whether the sphygmomanometer is in the nocturnal blood pressure measurement mode or in the measurement suspension state. 
     The sphygmomanometer of this embodiment allows the subject to check whether the sphygmomanometer is in the nocturnal blood pressure measurement mode or in the measurement suspension state by viewing the indicator lamp. 
     In the sphygmomanometer of one embodiment, wherein the measurement site is a wrist. 
     Since the sphygmomanometer of this embodiment compresses a wrist as the measurement site, it is expected that the sphygmomanometer hinders sleep of the subject to a smaller extent than a sphygmomanometer that compresses an upper arm (Imai et al., “Development and evaluation of a home nocturnal blood pressure monitoring system using a wrist-cuff device”, Blood Pressure Monitoring 2018, 23, P318-326). Therefore, this sphygmomanometer is suitable for nocturnal (sleep) blood pressure measurement. 
     In the sphygmomanometer of one embodiment, the sphygmomanometer comprises 
     a main body provided integrally with the blood pressure measurement cuff, wherein 
     the main body is equipped with the blood pressure measurement unit, the single operation switch, the suspension processing unit, and the recovery processing unit. Here, the “blood pressure measurement unit” includes, for example, a pump that supplies a pressurizing fluid to the blood pressure measurement cuff, a valve that releases the fluid from the blood pressure measurement cuff, and components that drive and control the pump, the valve, and the like. 
     The sphygmomanometer of this embodiment can be formed integrally and compactly. Therefore, the sphygmomanometer is handy for a user. 
     In another aspect, a blood pressure measurement method of the present disclosure for a sphygmomanometer that performs blood pressure measurement by temporarily compressing a measurement site of a subject with a blood pressure measurement cuff, 
     the sphygmomanometer 
     having a nocturnal blood pressure measurement mode in which blood pressure measurement automatically starts according to a schedule determined in advance, and 
     including a single operation switch for inputting an instruction to suspend the nocturnal blood pressure measurement mode or to recover to the nocturnal blood pressure measurement mode, 
     the blood pressure measurement method comprising: 
     automatically starting blood pressure measurement according to the schedule and measuring blood pressure when the blood pressure measurement cuff is in a pressurization process or a depressurization process, in the nocturnal blood pressure measurement mode; 
     performing a process for transitioning to a measurement suspension state in which blood pressure measurement does not start even when a clock time set in the schedule arrives, when the single operation switch is operated at a first time, in the nocturnal blood pressure measurement mode; and 
     performing a process for recovering to the nocturnal blood pressure measurement mode, under condition that the single operation switch is operated at a second time or after a lapse of a predetermined time from a clock time when the single operation switch is operated at the first time, in the measurement suspension state. 
     According to the blood pressure measurement method of the present disclosure, it is possible to prevent the start of blood pressure measurement scheduled in advance in the nocturnal blood pressure measurement mode while the subject is temporarily out of bed. 
     In yet another aspect, the computer-readable recording medium of the present disclosure is a computer-readable recording medium non-transitorily storing a program for causing a computer to execute the blood pressure measurement method. 
     The blood pressure measurement method can be implemented by making a computer read the program stored in the computer-readable recording medium of the present disclosure and causing a computer to execute the program. 
     As is clear from the above, according to the sphygmomanometer and the blood pressure measurement method of the present disclosure, it is possible to prevent the start of blood pressure measurement scheduled in advance in the nocturnal blood pressure measurement mode while the subject is temporarily out of bed. Furthermore, according to the program stored in the computer-readable recording medium of the present disclosure, it is possible to cause a computer to execute such a blood pressure measurement method. 
     The above embodiments are illustrative, and various modifications can be made without departing from the scope of the present invention. It is to be noted that the various embodiments described above can be appreciated individually within each embodiment, but the embodiments can be combined together. It is also to be noted that the various features in different embodiments can be appreciated individually by its own, but the features in different embodiments can be combined.