Patent Publication Number: US-2020297216-A1

Title: Physiological monitoring system and control method for a vital-sign detection device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/820,911, filed on Mar. 20, 2019, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a physiological monitoring system, and more particularly to a physiological monitoring system which can automatically control a photoplethysmography (PPG) sensor to emit at least one of visible light and invisible light. 
     Description of the Related Art 
     With aging societies, more and more burden is placed on hospital resources. Moreover, cardiovascular diseases are increasing, as people age and stress increases for modern day living. Thus, bio-signal self-measurement measurement devices have become an important target for development in the healthcare industry. Through sensing or detecting medically health information, such as electrocardiography (ECG), photoplethysmogram (PPG), heart rate, and blood pressure of patients in bio-signal self-measurement manners, the patients can monitor their own physiology status anytime, to relieve strain on hospital resources and provide needed medical attention to patients. Wearable devices are a hot topic these years. Some wearable devices are capable of tracking medically health information. Among various medically health information, the PPG information is important information which is correlated with the heart rate, oxyhemoglobin saturation (SPO2), blood pressure, sleep stage, occurrence of sleep apnea of the user wearing a wearable device. Generally, a PPG sensor which operates to obtain PPG information comprises a light emitter emitting visible light (such as green light with a better signal-noise ratio). However, when a PPG sensor operates to emit visible light to the user which is ready to sleep or is sleeping, light leakage from the PPG sensor may disadvantageously effect the sleep quality and the body&#39;s physiological clock of the user wearing the wearable device especially. 
     BRIEF SUMMARY OF THE INVENTION 
     An exemplary embodiment of a physiological monitoring system is provided. The physiological monitoring system comprises a vital-sign detection device and a controller. The vital-sign detection device emits visible light during a first period to detect a vital-sign of an object. During the first period, the controller determines whether a first predetermined event occurs. In response to the first predetermined event occurring, the controller controls the vital-sign detection device to emit invisible light during a second period to detect the vital-sign. 
     An exemplary embodiment of a control method for a vital-sign detection device. The control method comprises the steps of controlling the vital-sign detection device to emit visible light during a first period to detect a vital-sign of an object; during the first period, determining whether a first predetermined event occurs; and in response to the first predetermined event occurring, controlling the vital-sign detection device to emit invisible light during a second period to detect the vital-sign. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  shows one exemplary embodiment of a physiological monitoring system; 
         FIGS. 2A and 2B  are schematic diagrams showing a vital-sign detection device according to exemplary embodiments; 
         FIG. 3  shows an exemplary embodiment of a control method for the vital-sign detection device; 
         FIGS. 4A and 4B  are a schematic diagrams showing emitting states of visible light and invisible light according to exemplary embodiments; 
         FIG. 5  is flow chart showing details of the step S 31  of  FIG. 3  according to an exemplary embodiment; 
         FIGS. 6A and 6B  are schematic diagrams showing variation in motion of a user detected by a motion detector according to an exemplary embodiment; 
         FIG. 7  is a schematic diagram showing variation in a heart rate of a user detected by a heart-rate detector according to an exemplary embodiment; 
         FIG. 8  is flow chart showing details of the step S 34  of  FIG. 3  according to an exemplary embodiment; and 
         FIG. 9  is a schematic diagram showing various apparatus in the physiological monitoring system of  FIG. 1  according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated model of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       FIG. 1  shows one exemplary embodiment of a physiological monitoring system. As shown in  FIG. 1 , a physiological monitoring system  1  is provided. In the embodiment, the physiological monitoring system  1  operates to monitor at least one vital-sign of an object, such as a user, to generate a vital-sign signal. In an embodiment, the monitored vital-sign is the photoplethysmography (PPG) of the user using or wearing the physiological monitoring system  1 . The physiological monitoring system  1  can automatically control a photoplethysmography (PPG) sensor to emit invisible light before the user falls asleep or during the period when the user is sleeping and then control the PPG sensor to emit visible light in response to the user awaking from the sleep. As shown in  FIG. 1 , the physiological monitoring system  1  comprises a memory  10 , a plurality of detectors  11 , a controller  12 , and a vital-sign detection device  13 . In another embodiment, the vital-sign detection system  1  further comprises a smart home device  14  which can communicate with electronic products/devices in the user&#39;s place, such as smart lamps. The memory  10  may store preset sleep time which was input previously by the user or obtained from historical sleep time calculated by the controller  12  (the detailed description will be shown later). According to an embodiment, the plurality of detectors  11  comprises a light detector  110 , a motion detector  111 , and a heart-rate (HR) detector  112 . The vital-sign detection device  13  may emit visible light and invisible light for sensing pulses of a blood vessel of the user to generate a vital-sign signal S 13 . According to the embodiment, the visible light can be the light whose wavelength is in a range from about 380 nm to about 760 nm, and the invisible light can be the light whose wavelength is less than about 380 nm or larger than about 760 nm. For example, in an embodiment, the visible light is green light, and the invisible light is infrared. As shown in  FIG. 2A , the vital-sign detection device  13  comprises a PPG sensor  130 , and the PPG sensor  130  comprises one light emitter  1300  which can emit light having an adjustable wavelength. The light emitter  1300  is controlled by the controller  12  to adjust the adjustable wavelength of the light, so that the light emitter  1300  emits visible light or invisible light through the adjustment of the adjustable wavelength. The position of the light emitter  1300  shown in  FIG. 2A  is an example for illustrating the light emitting from the PPG sensor  130 , and the real position of the light emitter  1300  in the PPG  130  is determined according to the system design. In another embodiment, as shown in  FIG. 2B , the PPG sensor  130  comprises a light emitter  1300 A which is configured to emit visible light and a light emitter  1300 B which is configured to emit invisible light. Since the light emitters  1300 A and  1300 B are independence from each other, the controller  12  can control the vital-sign detection device  130  to emit at least one of the visible light from the light emitter  1300 A and the invisible light from the light emitter  1300 B at a time. Thus, the period when the light emitter  1300 A emits the visible light does not overlap the period when the light emitter  1300 B emits the invisible light or the period when the light emitter  1300 A emits the visible light partially overlaps the period when the light emitter  1300 B emits the invisible light. The positions of the light emitters  1300 A and  1300 B shown in  FIG. 2B  are an example for illustrating the light emitting from the PPG sensor  130 , and the real positions of the light emitters  1300 A and  1300 B in the PPG  130  is determined according to the system design. The controller  12  generates a control signal S 12  and controls the vital-sign detection device  13  through the control signal S 12  according to the signals/data from the memory  10 , the plurality of detectors  11 , and/or the smart home device  13 . 
       FIG. 3  shows an exemplary embodiment of a control method for the vital-sign detection device  13 . Referring to  FIG. 3 , the vital-sign detection device  13  initially emits the visible light from the PPG sensor  130  (Step S 30 ). Referring to  FIGS. 4A and 4B , the labels  40  and  41  represents the emitting states of the visible light and the invisible light respectively, wherein “ON” indicates that the corresponding light is being emitted by the PPG sensor  130 , while “OFF” indicates that the light is not being emitted by the PPG sensor  130 . In  FIGS. 4A and 4B , the vital-sign detection device  13  initially emits the visible light during the period P 40  ( 40 : ON). Referring to  FIG. 3  again, the controller  12  then determines whether a first predetermined event occurs during the period P 40  when the vital-sign detection device  13  emits the visible light (Step S 31 ). In the embodiment, the first predetermined event indicates that the user is in a ready-to-sleep status which occurs before the user falls asleep (such as, a state in which the user is in a lying posture or still for a while) or the user is sleeping (such as, the user breathes regularly). If the controller  12  determines that the first predetermined event does not occur, the step S 31  is performed repeatedly. Once the controller  12  determines that the first predetermined event occurs, the controller  12  determines that the user is in the ready-to-sleep status or is sleeping (Step S 32 ) and controls the vital-sign detection device  13  to emit the invisible light ( 41 : ON) through the control signal S 12  (Step S 33 ). In one embodiment, referring to  FIG. 4A , when the controller  12  determines that the first predetermined event occurs at the time point T 40 , the controller  12  controls the PPG sensor  130  to stop emitting the visible light ( 40 : OFF) and emit the invisible light ( 41 : ON) at the same time point T 40 . Thus, during the period P 41  starting from the time point T 40 , the PPG sensor  130  emits the invisible light ( 41 : ON), but does not emit the visible light ( 40 : OFF). In this embodiment, the period P 41  when the invisible light is emitted ( 41 : ON) does not overlap the period P 40  when the visible light is emitted ( 40 : ON). In another embodiment, referring to  FIG. 4B , when the controller  12  determines that the first predetermined event occurs at the time point T 40 , the controller  12  controls the PPG sensor  130  to emit the invisible light ( 41 : ON) at the time point T 40 . Then, at the time point T 40 ′ occurring after the time point T 40 , the controller  12  controls the PPG sensor  130  to stop emitting the visible light ( 40 : OFF). Thus, the PPG sensor  130  emits the invisible light ( 41 : ON) during the period P 43  starting from the time point T 40 , and the PPG sensor  130  does not emit the visible light ( 40 : OFF) during the period P 43  starting from the time point T 40 ′. In this embodiment, the period P 43  when the invisible light is emitted ( 41 : ON) partially overlaps the period P 40  when the visible light is emitted ( 40 : ON) as shown by the oblique lines in  FIG. 4B , wherein the period P 40  ends during the period P 43 . 
     In an embodiment, the controller  12  defines each time point T 40  when the first predetermined event occurs as a sleep time. When the controller  12  obtains at least one time point T 40 , the controller  12  calculates historical sleep time according to the least one time points T 40  by using statistical manners and provides a signal which contains information about the historical sleep time to the memory  10  for updating the preset sleep time. 
     During the period P 41  ( FIG. 4A )/P 43  ( FIG. 4B ) when the PPG sensor  130  emits the invisible light, the controller  12  determines whether a second predetermined event occurs (step S 34 ). In the embodiment, the second predetermined event indicates that the user awakes from the sleep. If the controller  12  determines that the second predetermined event does not occur, the step S 34  is performed repeatedly, and, at this time, the PPG sensor  130  continuously emits only the invisible light. Once the controller  12  determines that the second predetermined event occurs, the controller  12  determines that the user awakes from the sleep (Step S 35 ) and controls the vital-sign detection device  13  to emit the visible light ( 40 : ON) through the control signal S 12  (Step S 36 ). In one embodiment, referring to  FIG. 4A , when the controller  12  determines that the second predetermined event occurs at the time point T 41 , the controller  12  controls the PPG sensor  130  to stop emitting the invisible light ( 41 : OFF) and emit the visible light ( 40 : ON) at the same time point T 41 . Thus, during the period P 42  starting from the time point T 41 , the PPG sensor  130  emits the visible light ( 40 : ON), but does not emit the invisible light ( 41 : OFF). In this embodiment, the period P 42  when the visible light is emitted ( 40 : ON) does not overlap the period P 41  when the invisible light is emitted ( 41 : ON). In another embodiment, referring to  FIG. 4B , when the controller  12  determines that the first predetermined event occurs at the time point T 41 , the controller  12  controls the PPG sensor  130  to emit the visible light ( 40 : ON) at the time point T 41 . Then, at the time point T 41 ′ occurring after the time point T 41 , the controller  12  controls the PPG sensor  130  to stop emitting the invisible light ( 41 : OFF). Thus, the PPG sensor  130  emits the visible light ( 40 : ON) during the period P 42  starting from the time point T 41 , and the PPG sensor  130  does not emit the invisible light ( 41 : OFF) during the period P 44  starting from the time point T 41 ′. In this embodiment, the period P 42  when the visible light is emitted ( 40 : ON) partially overlaps the period P 43  when the invisible light is emitted ( 41 : ON) as shown by the oblique lines in  FIG. 4B , wherein the period P 43  ends during the period P 42 . 
     In the above, the emitting states of the visible light and the invisible light shown in  FIG. 4A  can be achieved by using the PPG sensor  130  of  FIG. 2A  or the PPG sensor  130  of  FIG. 2B , while the emitting states of the visible light and the invisible light shown in  FIG. 4A  can be achieved by using the PPG sensor  130  of  FIG. 2B . 
     According to the embodiment, the physiological monitoring system  1  can automatically control the PPG sensor  130  to stop emitting the visible light and begin emitting the invisible light before the user falls asleep or during the period when the user is sleeping. The physiological monitoring system  1  can also automatically control the PPG sensor  130  to begin emitting visible light in response to the user awaking from the sleep. Thus, during the period when the user is sleeping, the visible light cannot be sensed by the eyes of the user, thereby avoiding affecting the sleep quality and the body&#39;s physiological clock of the user by the light leakage from the PPG sensor  130 . 
     In the embodiment, for determining whether the first predetermined event occurs in the step S 31 , the controller  12  sets a plurality of first conditions and determines whether each of the plurality of first conditions is met. In the embodiment, the controller  12  sets four first conditions. In the cases where some first conditions are met, the controller  12  determines whether the number (N) of the first conditions which are met is larger than a first threshold X. If the controller  12  determines that the number of the first conditions which are met is larger than the first threshold X, the controller  12  determines that the first predetermined event occurs. According to the embodiment, the first threshold (X) is set to be 70%˜80% of the total number of first conditions. For example, in the cases where there are four first conditions, the first threshold is set as 3 (X=3). In the following paragraphs, how the controller  12  determines whether the first predetermined event occurs will be described, that is, the detail of the step S 31  will be described. 
     In the embodiment, the controller  12  generates a counting value through a counting operation of an internal counter. Referring to  FIG. 5 , the controller  12  resets the counting value N to “0” (Step S 50 : N=0). Then, the controller  12  accesses the memory  10  to read the data D 10  containing the preset sleep time Tsleep and determines whether the preset sleep time Tsleep is reached (Step S 51 A). In  FIG. 5 , the step S 51 A is represented as “determine whether Tsleep is reached?” Once the preset sleep time Tsleep is reached, the controller  12  determines that one of the plurality of first conditions is met and increases the counting value N by “1” (Step S 52 : N+1). If the preset sleep time Tsleep is not reached yet, the controller  12  continuously determines whether the preset sleep time Tsleep is reached (Step S 51 A), and the flow proceeds to the step S 51 B. 
     Referring to  FIG. 5 , in the step S 51 B, the controller  12  determines whether a lamp near the vital-sign detection device  13  is turned off. If the controller  12  determines that lamp near the vital-sign detection device  13  is turned off, the controller  12  determines that one of the plurality of first conditions is met and increases the counting value N by “1” (Step S 52 : N+1). Referring to  FIG. 1 , the light detector  110  detects ambient light of the vital-sign detection device  13  and generates a light-detection signal S 110  according to the detected ambient light. The controller  12  receives the light-detection signal S 110  and analyzes the light-detection signal S 111  to obtain the intensity of the ambient light which can indicate the on/off state of the lamp. In an embodiment, whether the lamp near the vital-sign detection device  13  is turned off is determined according to the intensity of the ambient light. According to an embodiment, the intensity of the ambient light is obtained by the following algorithm. First, the controller  12  calculates the mean value of the luminous flux (lux) of the detected ambient light in 1 minute, wherein the calculated mean value serves as the above intensity of the ambient light. The controller  12  determines whether the calculated mean is less than a first predetermined threshold (such as 5 lm) for more than a predetermined period (such as, 5 minutes) and further determines whether the calculated mean is larger than a second predetermined threshold (such as 50 lm) for more than the predetermined period (5 minutes). If the calculated mean is less than 5 lm for more than 5 minutes, the controller  12  determines that the lamp near the vital-sign detection device  13  is turned off, which can represent that the user is in the ready-to-sleep status or is sleeping. If the calculated mean is larger than 50 lm for more than 5 minutes, the controller  12  determines that the lamp near the vital-sign detection device  13  is not turned off (that is, the lamp is turned on), which can represent that the user is not in the ready-to-sleep status and not sleeping. 
     In another embodiment, in the cases where the lamp near the vital-sign detection device  13  is a smart lamp, the smart home device  14  can communicate with the smart lamp to control its on/off state and then generate an indication signal S 14  according to the current on/off state of the smart lamp. The controller  12  receives the indication signal S 14  and determines whether the smart lamp is turned off according to the indication signal S 14 . 
     Referring to  FIG. 5 , after the determination at the step S 51 B is done, the controller  12  determines whether the motion of the user belongs to a specific type (Step S 51 C). In the embodiment, the specific type indicates that the user is in a lying posture, is still for a while, or breathes regularly which can be represented by regular moving of the thoracic cavity of the user. For example, the specific type indicates that the user is in a lying posture and/or still for a while. Referring to  FIG. 1 , the motion detector  111  detects the motion of the user and generates a motion signal S 111  according to the detected motion. The motion sensor  112  provides the motion signal S 111  to the controller  12 . In the embodiment, the motion detector  111  may comprise at least one device which can provide motion information of a specific object detected or monitored by the least one device, such as at least one of an accelerometer, a gyroscope, and a camera. The motion information indicates whether the user is in a laying posture or still for a while or breathes regularly. In the following, an embodiment where the motion detector  111  detects the motion of the user by a gyroscope will be described. Based on a general operation of a gyroscope, the signal generated by the gyroscope contains three components: X-axis component, Y-axis component, and Z-axis component. Accordingly, the motion signal S 111  generated by the motion sensor  111  contains an X-axis component, a Y-axis component, and an Z-axis component for the gyroscope. Referring to  FIG. 6A , in the cases where the user is lying on the bed and sleeping during the period P 60 , the value of the X-axis is less during the period P 60 , for example, the value of the X-axis component is less than 1 g (9.8 m/s 2 ). Thus, in the embodiment, the controller  12  determines whether the value of the X-axis component contained in the motion signal S 111  is less than a predetermined threshold VH 60 , such as 1 g (9.8 m/s 2 ), thereby determining whether the user is in a lying posture. If the value of the X-axis component is less than the predetermined threshold VH 60 , the controller  12  determines that the user is in the lying posture (that is, the motion of the user belongs to the specific type) and determines that one of the plurality of first conditions is met. Then, the controller  11  increases the counting value N by “1” (Step S 52 : N+1). 
     Referring to  FIG. 6B , during the period P 60  when the user is lying on the bed and sleeping, the activity of the user is less. Thus, in another embodiment, the controller  12  receives the motion signal S 111  and analyzes it to obtain the activity of the user. The controller  12  determines whether the obtained activity of the user is less than a predetermined threshold VH 61  (such as 50) for more than a predetermined period (for example, 5 minutes), thereby determining whether the user is still for a while. If the obtained activity of the user is less than 50 for 5 minutes, the controller  12  determines that the user is still for a while (that is, the motion of the user belongs to the specific type) and determines that one of the plurality of first conditions is met. Then, the controller  12  increases the counting value N by “1” (Step S 52 : N+1). 
     According to an embodiment, the activity of the user is obtained by the following algorithm. The values of the X-axis component, Y-axis component, and Z-axis component of the gyroscope are represented by x, y, and z respectively. After receiving the motion signal S 111 , the controller  12  calculates the square root of the sum of the square of x, the square of y, and the square of z to obtain an original activity value Activity_original (Activity_original=Sqet(x 2 +y 2 +z 2 ). Then, the controller  12  performs high pass filtering (HPF) on the original activity value Activity_original to obtain a filtered activity value Activity_filtered (Activity_filtered=HPF(Activity_original)). The controller  12  calculates the mean value of the filtered activity values Activity_filtered which are obtained every 10 minutes to obtain a mean activity MA_Activity (MA_Activayr=mean (Activity_filtered in 10 minutes)), wherein the mean activate MA_Activity serves as the above the activity of the user. Then, the controller  12  determines whether the mean activate MA_Activity is less than 50 for more than 5 minutes ((MA_Activity&lt;50) over 5 minutes). If the mean activate MA_Activity is less than 50 for more than 5 minutes, the controller  12  determines that the user is still for a while and determines that one of the plurality of first conditions is met. 
     In another embodiment, the controller  12  may determine whether the motion of the user belongs to the specific type by determining whether the user is in a lying posture and determining whether the user is still for a while. If the controller  12  determines that the user is in the lying posture, that the user is still for a while, or that the user is in the lying posture and sill for a while, the controller  12  determines that the motion of the user belongs to the specific type. 
     Referring to  FIG. 5 , after the determination at the step S 51 C is done, the controller  12  determines whether the heart rate of the user becomes lower (Step S 51 D). Referring to  FIG. 1 , the heart-rate detector  112  may receive the vital-sign signal S 13  from the vital-sign detection device  13  and/or an ECG signal S 14  from an ECG monitor and obtain the heart rate of the user according to the vital-sign detection device  13  and/or the ECG signal S 14 . How to obtain a heart rate of a user contacting a PPG sensor or an ECG monitor is well known by the one skilled in the art, thus, the related description is omitted here. The heart-rate detector  112  generates a detection signal S 112  according to the obtained heart rate. Referring to  FIG. 7 , in the cases where the user is sleeping during the period P 70 , the heart rate value of the user is less during the period P 70 , for example, the average of the heart rate is 56.7 bpm. Thus, in the embodiment, the controller  12  receives the detection signal S 112 , obtains the heart rate of the user from the detection signal S 112 , and determines whether the heart rate of the user becomes lower than a predetermined threshold VH 70  for more than a predetermined period, thereby determining whether the user is sleeping. If the heart rate of the user becomes lower than the predetermined threshold VH 70  for more than the predetermined period, the controller  12  determines that the user is sleeping and determines that one of the plurality of first conditions is met. Then, the controller  11  increases the counting value N by “1” (Step S 52 : N+1). 
     After the steps S 51 A˜S 51 D are done, the counting value N represents the number of first conditions are met. The controller  12  determines whether the counting value N is larger than the first threshold X (Step S 53 : N&gt;X (X=3)?). If the controller  12  determines that the counting value N is larger than the first threshold X, the controller  12  determines that the first predetermined event occurs, and the flow proceeds to the step S 32  of  FIG. 3 . If the controller  12  determines that the counting value N is not larger than the first threshold X, the controller  12  determines that the first predetermined event does not occur, and the step S 31  is performed repeatedly. 
     In the embodiment, for determining whether the second predetermined event occurs in the step S 34 , the controller  12  sets a plurality of second conditions and determines whether each of the plurality of second conditions is met. In the embodiment, the controller  12  sets three second conditions. In the cases where some second conditions are met, the controller  12  determines whether the number (M) of the second conditions which are met is larger than a second threshold Y. If the controller  12  determines that the number (M) of the second conditions which are met is larger than the second threshold Y, the controller  12  determines that the second predetermined event occurs. According to the embodiment, the second threshold (Y) is set to be 65%˜80% of the total number of second conditions. For example, in the cases where there are three second conditions, the second threshold is set as 2 (Y=2). In the following paragraphs, how the controller  12  determines whether the second predetermined event occurs will be described, that is, the detail of the step S 34  will be described. 
     In the embodiment, the controller  12  generates a counting value M through a counting operation of another internal counter. Referring to  FIG. 8 , the controller  12  resets the counting value M to “0” (Step S 80 : M=0). Then, the controller  12  determines whether a lamp near the vital-sign detection device  13  is turned on (Step S 81 A). If the controller  12  determines that lamp near the vital-sign detection device  13  is turned on, the controller  12  determines that one of the plurality of second conditions is met and then increases the counting value M by “1” (Step S 82 : M+1). As described above, the controller  12  determines whether the intensity of the ambient light (the mean value of the luminous flux (lux) of the detected ambient light in 1 minute) is less than 5 lm for more than a predetermined period (such as, 5 minutes) and further determines whether the intensity of the ambient light is larger than 50 lm for more than 5 minutes. If the calculated mean is larger than 50 lm for more than 5 minutes, the controller  12  determines that the lamp near the vital-sign detection device  13  is turned on, which can represent that the user awakes from the sleeping. If the calculated mean is less than 5 lm for more than 5 minutes, the controller  12  determines that the lamp near the vital-sign detection device  13  is turned off, which can represent that the user is still sleeping. 
     Referring to  FIG. 6B , when the user awakes from the sleep during the period P 61 , the activity of the user becomes larger. Thus, as shown in  FIG. 8 , after the determination at the step S 81 A is done, the controller  12  determines whether the activity of the user becomes larger (Step S 81 B), thereby determining whether the user awakes from the sleep. In the embodiment, the controller  12  determines whether the activity of the user becomes larger than the predetermined threshold VH 61  for more than a predetermined period (for example, 5 minutes). If the obtained activity of the user is larger than the predetermined threshold VH 61  for 5 minutes, the controller  12  determines that the user awakes from the sleep and determines that one of the plurality of second conditions is met. Then, the controller  12  increases the counting value M by “1” (Step S 82 : M+1). If the obtained activity of the user does not become larger than the predetermined threshold VH 61  for 5 minutes, the controller  12  determines that the user is still sleeping. 
     Referring to  FIG. 7 , when the user awakes from the sleep during the period P 71 , the heart rate value of the user becomes higher, for example, the average of the heart rate is 76.2 bpm. Thus, as shown in  FIG. 8 , after the determination at the step S 81 B is done, in the embodiment, the controller  12  determines whether the heart rate of the user becomes higher (Step S 81 C), thereby determining whether the user awakes from the sleep. According to an embodiment, in the Step S 81 C, the controller  12  determines whether the heart rate of the user becomes higher than the predetermined threshold VH 70  for more than a predetermined period. If the heart rate of the user becomes higher than the predetermined threshold VH 70  for more than the predetermined period, the controller  12  determines that the user awakes from the sleep and determines that one of the plurality of second conditions is met. Then, the controller  12  increases the counting value M by “1” (Step S 82 : M+1). If the heart rate of the user does not become higher than the predetermined threshold VH 70  for more than the predetermined period, the controller  12  determines the controller  12  determines that the user is still sleeping. 
     After the steps S 81 A˜S 81 C are done, the counting value M represents the number of second conditions are met. The controller  12  determines whether the counting value M is larger than the second threshold Y (Step S 83 : M&gt;Y (Y=2)?). If the controller  12  determines that the counting value M is larger than the first threshold Y, the controller  12  determines that the second predetermined event occurs, and the flow proceeds to the step S 35  of  FIG. 3 . If the controller  12  determines that the counting value M is not larger than the first threshold Y, the controller  12  determines that the second predetermined event does not occur, and the step S 34  is performed repeatedly. 
     In an embodiment, the physiological monitoring system  11  comprises several apparatus, and the devices/elements shown in  FIG. 1  can be disposed on these apparatus. Referring to  FIG. 9 , in addition to the smart home device  14 , the vital-sign detection system  1  further comprises two apparatus: a main apparatus  90  and a wearable apparatus  91 . For example, the main apparatus  90  can be a smart phone, while the wearable apparatus  91  is a smart watch worn by the user. According to the above description, the motion detector  111  and the vital-sign detection device  13  are disposed on the smart watch  91  based on their operations and functions. In an embodiment, the memory  10  can be disposed on the smart phone  90  or the smart watch  91 , and the data D 10  in the memory  10  related to the sleep time is input by the user previously or obtained from historical sleep time detected by the controller  12 . In an embodiment, the light detector  110  may be disposed on the smart phone  90  or the smart switch  91 . In another embodiment, the light detector  110  may be disposed on the smart home device  14  in the cases where the smart home device  14  is on the location where the user sleeps, such as, the user&#39;s bedroom. The controller  12  is disposed on smart phone  90  or smart watch  91 . In other embodiment, the controller  12  can be implemented by the processor of the smart phone  90  or smart watch  91 . 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.