Patent Publication Number: US-2021178164-A1

Title: Method and apparatus for pain management with sleep detection

Description:
CLAIM OF PRIORITY 
     This application is a continuation of U.S. application Ser. No. 15/888,808, filed Feb. 5, 2018, which claims the benefit of priority under 35 § 119(e) of U.S. Provisional Patent Application Ser. No. 62/457,456, filed on Feb. 10, 2017, each of which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This document relates generally to medical devices and more particularly to a pain management system that determines sleep state and control pain management based on the sleep state. 
     BACKGROUND 
     Pain may result from an injury, a disease (e.g., arthritis, fibromyalgia), or even a medical treatment (e.g., certain cancer treatment). Various treatments are applied for pain management, such as medication, psychotherapy, electrical stimulation, thermal therapy, and their various combinations. Examples of electrical stimulation for pain management include Transcutaneous Electrical Nerve Stimulation (TENS) delivered by a TENS unit and Spinal Cord Stimulation (SCS) that may be delivered by an implantable neuromodulation systems. Pain treatment may be prescribed based on an assessment of a patient&#39;s symptoms and underlying conditioning and titrated based on the patient&#39;s response to the treatment. As pain is not directly measurable by a machine, the assessment of the condition and the titration of the therapy may depend on questioning the patient. Because pain is affected by various factors, such as physical, physiological, and mental states of the patient, that vary with time, dependency on patient feedback limits timely adjustment or optimization of a pain suppression therapy. 
     SUMMARY 
     An Example (e.g. “Example 1”) of a system for providing a patient with pain management may include a sleep monitoring circuit, a pain relief device, and a control circuit. The sleep monitoring circuit may be configured to sense one or more sleep signals from the patient and to determine a sleep state of the patient using the one or more sleep signals. The one or more sleep signals may include one or more physiological signals corresponding to the sleep state of the patient. The pain relief device may be configured to deliver one or more pain relief therapies. The control circuit may be configured to control the delivery of the one or more pain relief therapies using therapy parameters and to adjust the therapy parameters based on the determined sleep state. 
     In Example 2, the subject matter of Example 1 may optionally be configured to include an implantable medical device that includes at least portions of the sleep monitoring circuit, the pain relief device, and the control circuit. 
     In Example 3, the subject matter of any one or any combination of Examples 1 and 2. may optionally be configured such that the pain relief device includes a neurostimulator configured to deliver neurostimulation, and the control circuit is configured to control the delivery of the neurostimulation using stimulation parameters and adjust the stimulation parameters based on the determined sleep state. 
     In Example 4, the subject matter of any one or any combination of Examples 1 to 3 may optionally be configured such that the sleep monitoring circuit includes one or more sleep sensors configured to sense the one or more sleep signals from the patient, a sleep signal sensing circuit configured to process the one or more sleep signals, a sleep parameter generator circuit configured to generate one or more sleep parameters corresponding to the sleep state of the patient using the processed one or more sleep signals, and a sleep analyzer circuit to determine the sleep state of the patient using the generated one or more sleep parameters and a predetermined relationship between values of the one or more sleep parameters and the sleep state of the patient. 
     In Example 5, the subject matter of Example 4 may optionally be configured such that the one or more sleep sensors include one or more implantable sensors. 
     In Example 6, the subject matter of any one or any combination of Examples 4 and 5 may optionally be configured such that the one or more sleep sensors include one or more externally wearable sensors. 
     In Example 7, the subject matter of any one or any combination of Examples 4 to 6 may optionally be configured such that the sleep analyzer circuit includes a sleep parameter analyzer circuit configured to receive and analyze the generated one or more sleep parameters and a sleep score generator circuit configured to compute a sleep score using an outcome of the analysis of the generated one or more sleep parameters. The sleep score is indicative of the sleep state of the patient and includes one or more of a number, a sleep signal metric, or a number being a function of the sleep signal metric. The control circuit is configured to adjust the therapy parameters using the computed sleep score. 
     In Example 8, the subject matter of any one or any combination of Examples 4 to 7 may optionally be configured to further include a pain monitoring circuit configured to receive and analyze the sleep state and one or more of a physiological parameter indicative of a physiological function or physiological state of the patient, a functional parameter indicative of a physical activity or physical state of the patient, or a patient parameter including subjective information provided by the patient and to compute a pain score using an outcome of the analysis. The pain score indicates a degree of the pain of the patient. The control circuit is configured to adjust the therapy parameters using the pain score. 
     In Example 9, the subject matter of any one or any combination of Examples 4 to 8 may optionally be configured such that the one or more sleep sensors include a three-axis accelerometer configured to sense an accelerometer signal of the one or more sleep signals. 
     In Example 10, the subject matter of any one or any combination of Examples 4 to 9 may optionally be configured such that the one or more sleep sensors include a three-axis gyroscope configured to sense a gyroscope signal of the one or more sleep signals. 
     In Example 11, the subject matter of any one or any combination of Examples 4 to 10 may optionally be configured such that the one or more sleep sensors include an electrocardiogram (ECG) sensor configured to sense an ECG signal of the one or more sleep signals. 
     In Example 12, the subject matter of any one or any combination of Examples 4 to 11 may optionally be configured such that the one or more sleep sensors include an electroencephalogram (EEG) sensor configured to sense an EEG signal of the one or more sleep signals. 
     In Example 13, the subject matter of any one or any combination of Examples 4 to 12 may optionally be configured such that the one or more sleep sensors include a temperature sensor configured to sense a temperature signal of the one or more sleep signals. 
     In Example 14, the subject matter of any one or any combination of Examples 4 to 13 may optionally be configured such that the one or more sleep sensors include an electrodermal activity (EDA) sensor configured to sense an EDA signal of the one or more sleep signals. 
     In Example 15, the subject matter of any one or any combination of Examples 4 to 14 may optionally be configured such that the one or more sleep sensors include a blood volume pulse (BVP) sensor configured to sense a BVP signal of the one or more sleep signals. 
     An example (e.g., “Example 16”) of a method for providing a patient with pain management is also provided. The method may include sensing one or more sleep signals from the patient, determining the sleep state of the patient using the one or more sleep signals, controlling the delivery of one or more pain relief therapies using therapy parameters, adjusting the therapy parameters based on the determined sleep state, and delivering the one or more pain relief therapies. The one or more sleep signals may include one or more physiological signals corresponding to a sleep state of the patient. 
     In Example 17, the subject matter of determining the sleep state as found in Example 16 may optionally further include determining a sleep stage. 
     In Example 18, the subject matter of delivering the one or more pain relief therapies as found in Example 17 may optionally further include delivering neurostimulation, and the subject matter of adjusting the therapy parameters based on the determined sleep state as found in Example 17 may optionally further include adjusting stimulation parameters based on the determined sleep stage. 
     In Example 19, the subject matter of determining the sleep stage as found in any one or any combination of Examples 17 and 18 may optionally further include producing a sleep score using the one or more sleep signals, and the subject matter of adjusting the therapy parameters based on the determined sleep state as found in any one or any combination of Examples 17 and 18 may optionally further include adjusting the therapy parameters based on the produced sleep score. The sleep score is indicative of the sleep stage and includes one or more of a number, a sleep signal metric, or a number being a function of the sleep signal metric. 
     In Example 20, the subject matter of any one or any combination of Examples 16 to 19 may optionally further include receiving and analyzing the determined sleep state and one or more of a physiological parameter indicative of a physiological function or physiological state of the patient, a functional parameter indicative of a physical activity or physical state of the patient, or a patient parameter including subjective information provided by the patient and to compute a pain score using an outcome of the analysis, the pain score indicating a degree of the pain of the patient, and the subject matter of adjusting the therapy parameters based on the determined sleep state as found in any one or any combination of Examples 16 to 19 may optionally include adjusting the therapy parameters based on the pain score. 
     In Example 21, the subject matter of sensing the one or more sleep signals from the patient as found in any one or any combination of Examples 16 to 20 may optionally further include sensing one or more of an accelerometer signal, a gyroscope signal, an electrocardiogram (ECG) signal, an electroencephalogram (EEG) signal, a temperature signal of the one or more sleep signals, an electrodermal activity (EDA) signal, a blood volume pulse (BVP) signal, or a bioelectric impedance signal. 
     In Example 22, the subject matter of delivering one or more pain relief therapies as found in any one or any combination of Examples 16 to 21 may optionally further include delivering the one or more pain relief therapies from a medical device implanted in the patient or externally worn by the patient. 
     In Example 23, the subject matter of sensing the one or more sleep signals as found in any one or any combination of Examples 16 to 22 may optionally further include sensing at least one sleep signal of the one or more sleep signals using a sensor implanted in the patient. 
     In Example 24, the subject matter of sensing the one or more sleep signals as found in any one or any combination of Examples 16 to 23 may optionally further include sensing at least one sleep signal of the one or more sleep signals using a sensor externally worn by the patient. 
     In Example 25, the subject matter of sensing the one or more sleep signals as found in any one or any combination of Examples 22 to 24 may optionally further include sensing at least one sleep signal of the one or more sleep signals using a sensor communicatively coupled to the medical device via a wireless link. 
     This Summary is an overview of some of the teachings of the present application and not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details about the present subject matter are found in the detailed description and appended claims. Other aspects of the disclosure will be apparent to persons skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which are not to be taken in a limiting sense. The scope of the present disclosure is defined by the appended claims and their legal equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate generally, by way of example, various embodiments discussed in the present document. The drawings are for illustrative purposes only and may not be to scale. 
         FIG. 1  illustrates an embodiment of a therapy system. 
         FIG. 2  illustrates an embodiment of a sleep monitoring circuit, such as may be used in the therapy system of  FIG. 1 . 
         FIG. 3  illustrates another embodiment of a sleep monitoring circuit, such as may be used in the therapy system of  FIG. 1 . 
         FIG. 4  illustrates an embodiment of a pain management system. 
         FIG. 5  illustrates another embodiment of pain management system. 
         FIG. 6  illustrates an embodiment of a pain monitoring circuit, such as may be used in the therapy system of  FIG. 5 . 
         FIG. 7  illustrates an embodiment of a pain management system, such as one in which the pain management system of  FIG. 4 or 5  may be implemented, and portions of an environment in which the pain management system may be used. 
         FIG. 8  illustrates an embodiment of a method for pain management. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention. References to “an”, “one”, or “various” embodiments in this disclosure are not necessarily to the same embodiment, and such references contemplate more than one embodiment. The following detailed description provides examples, and the scope of the present invention is defined by the appended claims and their legal equivalents. 
     This document discusses, among other things, a system for controlling delivery of a therapy to a patient based on sleep state of the patient. Conditions, such as chronic pain, can be affected by the patient&#39;s sleep state and quality, and also affects the patient&#39;s sleep state and quality. Chronic therapies, such as a therapy for controlling chronic pain, needs optimization of settings during wakefulness that differ from those during sleep to maximize its therapeutic benefits to the patient. Sleep quality is an important therapeutic outcome and is associated with the patient&#39;s overall health status. However, it is not often measured and used in demonstrating therapeutic efficacy. For example, to control delivery of a pain suppression therapy automatically using a closed-loop system, there is a need to use the patient&#39;s sleep state as an input and/or as a measure of efficacy of the therapy. 
     Physiological conditions during sleep differ greatly from those during wakefulness, and thus treatment for chronic diseases must reflect those changes. For instance, in a chronic pain patient treated with spinal cord stimulation, levels of endogenous neurotransmitters during sleep may require lesser stimulation current to achieve pain reduction. In an algorithm designed to objectively measure pain, it would be important to distinguish changes in physiological parameters due to sleep changes compared to those due to pain. Because chronic pain patients often report disturbances with their sleep, stages and quality of sleep can be used as a surrogate for pain levels for controlling therapy delivery. Modulating therapy using the patient&#39;s sleep state can also save battery energy in an implantable device delivering a pain suppression therapy because less stimulation energy is needed during sleep. 
     Wakefulness can be differentiated from sleep using a range of different modalities, including electroencephalography (EEG), electrodermal activity (EDA), and heart rate. These modalities can be used to differentiate various stages of sleep. For example, studies showed that sleep epochs with EDA peaks are more common during slow-wave sleep than in rapid eye movement (REM) sleep. 
     Chronic pain patients are more likely than a healthy person to suffer from poor sleep quality and disturbances during sleep. Greater sleep disturbance was shown to be correlated to greater pain intensity, disability, depression, and physical symptoms. Often it is considered that sleep disruption is a consequence of pain. However, this in fact can be a bidirectional relation. Sleep, emotional distress, pain perception, daily physical activity appear to link to each other to form a cycle in the patient&#39;s daily experience. 
     In 2015, the National Sleep Foundation conducted a “Sleep in America Poll”, which resulted in a finding that pain was the main factor between the amounts of sleep people said they needed and how much they got (sleep gap), with chronic pain having a larger discrepancy than those with acute pain. In addition, pain, stress, and poor health were the key correlates of shorter sleep durations and worse sleep quality. However, for those who make sleep a priority, the sleep gap narrows sharply and is associated with less stress and better health. 
     The present system can include a therapeutic medical device, such as a spinal cord stimulator or intrathecal drug pump, that monitors physiological signals from wearable and/or implantable sensors to determine a patient&#39;s stages of sleep and controls delivery of a therapy based on the stage of sleep. In various embodiments, the stage of sleep can be used as an input signal in an automated closed-loop therapy control system and/or as a guide for a user adjusting the therapy. In this document, a “user” can include a physician or other care provider who treats the patient using the present system. While pain management is discussed as a specific example of application, the present subject matter can be applied in controlling and/or optimizing any therapy based on sleep states. For example, the present subject matter can also be used to control and/or optimize a therapy for improving sleep (e.g., a spinal cord stimulation therapy) that potentially provides a more natural human sleep pattern, increased rapid eye movement (REM) sleep, etc. 
       FIG. 1  illustrates an embodiment of a therapy system  100  for delivering one or more therapies to a patient and controlling the delivery of the one or more therapies based on the patient&#39;s sleep state. Therapy system  100  can include a sleep monitoring circuit  102 , a control circuit  104 , and a therapy delivery device  106 . Sleep monitoring circuit  102  can sense one or more sleep signals from the patient, and can determine the sleep state of the patient using the one or more sleep signals. The one or more sleep signals can include one or more physiological signals corresponding to (or indicative of) the sleep state of the patient. The sleep state can include a sleep stage and/or one or more indicators of sleep quality such as time spent at each sleep stage and/or percentage of the time spent at each sleep stage during a sleeping period. Therapy delivery device  106  can deliver the one or more therapies for treating one or more pathological conditions in which sleep is an important factor, and/or in which improved sleep is a desirable outcome. For example, the one or more therapies may target at pain suppression and/or sleep quality improvement. Control circuit  104  can control the deliver of the one or more therapies from therapy delivery device  106  using therapy parameters and adjust the therapy parameters based on the sleep state. In various embodiments, control circuit  106  can optimize the therapy parameters for the determined sleep state. In various embodiments, control circuit  104  can execute a closed-loop therapy algorithm for treating the one or more pathological conditions using the determined sleep state as an input. 
     In various embodiments, circuits of system  100 , including its various embodiments discussed in this document, may be implemented using a combination of hardware and software. For example, sleep monitoring circuit  102  and control circuit  104 , including their various embodiments discussed in this document, may be implemented using an application-specific circuit constructed to perform one or more particular functions or a general-purpose circuit programmed to perform such function(s). Such a general-purpose circuit includes, but is not limited to, a microprocessor or a portion thereof, a microcontroller or portions thereof, and a programmable logic circuit or a portion thereof. 
       FIG. 2  illustrates an embodiment of a sleep monitoring circuit  202 , which represents an example of sleep monitoring circuit  102 . Sleep monitoring circuit  202  can include one or more sleep sensors  210 , a sleep signal sensing circuit  212 , a sleep parameter generator (or sleep parameter generator circuit)  214 , and a sleep analyzer (or sleep analyzer circuit)  216 . Sleep sensor(s)  210  can sense the one or more sleep signals from the patient. In various embodiments, sleep sensor(s)  210  can include one or more sensors each being incorporated into a medical device such as a medical device that includes control circuit  104  and therapy delivery device  106  or being another device communicatively coupled to the medical device via a wired or wireless communication link. In various embodiments, sleep sensor(s)  210  can include one or more sensors each being an implantable sensor or an externally wearable (non-implantable) sensor. The implantable sensor can be, for example, part of an implantable medical device that can include control circuit  104  and therapy delivery device  106  or being another implantable device communicatively coupled to the implantable medical device via a wired or wireless communication link. The externally wearable sensor can be, for example, part of an externally wearable medical device that can include control circuit  104  and therapy delivery device  106 , being another externally wearable device communicatively coupled to the externally wearable medical device via a wired or wireless communication link, or being an externally wearable device communicatively coupled to an implantable medical device that includes control circuit  104  and therapy delivery device  106  via a wired or wireless communication link. Sleep signal sensing circuit  212  can process the one or more sleep signals, such as by filtering and/or amplifying each sensed sleep signal. Sleep parameter generator  214  can generate one or more sleep parameters corresponding to (or indicative of) the sleep state of the patient using the processed one or more sleep signals. For example, sleep parameter generator  214  can detect specified features in each sensed sleep signal, measuring amplitude and/or time associated with the detected features, and generate one or more sleep parameters using results of the measurement. Sleep analyzer  216  can determine the sleep state of the patient using the one or more sleep parameters generated by sleep parameter generator  214 . Thus, the sleep state can be indicated by using information extracted from the one or more sleep signals sensed using one or more sensors  210 . 
       FIG. 3  illustrates another embodiment of a sleep monitoring circuit  302 , which represents an example of sleep monitoring circuit  202 . Sleep monitoring circuit  302  can include one or more sleep sensors  310 , a sleep signal sensing circuit  312 , a sleep parameter generator (or sleep parameter generator circuit)  314 , and a sleep analyzer (or sleep analyzer circuit)  316 . 
     Sleep sensor(s)  310  can sense the one or more sleep signals. In the illustrated embodiment, sleep sensor(s)  310  includes an accelerometer  310 A, a gyroscope  310 B, an electrocardiogram (ECG) sensor  310 C, an electroencephalogram (EEG) sensor  310 D, a temperature sensor  310 E, an electrodermal activity (EDA) sensor  310 F, a blood volume pulse (BVP) sensor  310 G, and an impedance sensor  310 H. In various embodiments, sleep sensor(s)  310  can include any one or any combination of accelerometer  310 A, gyroscope  310 B, ECG sensor  3100 , EEG sensor  310 D, temperature sensor  310 E, EDA sensor  310 F, BVP sensor  310 G, and impedance sensor  310 H. 
     Accelerometer  310 A can include a three-axis accelerometer to sense an accelerometer signal. In various embodiment, accelerometer  310 A can be an externally wearable device or an implantable device. In this document, a sensor being an externally wearable device include a stand-alone externally wearable sensor or a sensor being part of an externally wearable device that performs another one or more functions; a sensor being an implantable device include a stand-alone implantable sensor or a sensor being part of an implantable device that performs another one or more functions. An externally wearable device includes a device configured to be worn on the patient but not to be implanted in the patient. 
     Gyroscope  310 B can be a three-axis gyroscope to sense a gyroscope signal. In various embodiments, gyroscope  310 B can be an externally wearable device or an implantable device. 
     ECG sensor  3100  can include electrodes for sensing an ECG signal. In various embodiments, the ECG signal can include a surface ECG signal, a subcutaneous ECG signal, an epicardial electrogram signal, and/or an endocardial electrogram signal. ECG sensor  310 C can be an externally wearable device, part of therapy-delivering device (e.g., a cardiac pacemaker), or an injectable monitoring device. 
     EEG sensor  310 D can include electrodes for sensing an EEG signal. In various embodiments, EEG sensor  310 D can be an externally wearable device (e.g., incorporated into a head cap, one or more ear plugs, or a head band), a subdermally implantable device, or incorporated into an implantable lead in the brain or on a neural target. 
     Temperature sensor  310 E can sense a temperature signal. In various embodiments, temperature sensor  310 E can be an externally wearable device to measure skin temperature, a subdermally implantable device to measure peripheral body temperature, or an implantable device to measure core body temperature. 
     EDA sensor  310 F can sense an EDA signal. In various embodiments, EDA sensor  310 F can be a device with surface electrode to measure skin conductance, such as from a hand (palmar surface), a foot (plantar surface), or a wrist (incorporated into a wrist worn monitoring device) or an implantable device that is communicatively coupled to a conductive layer (tattoo) on the skin. 
     BVP sensor  310 G can sense a BVP signal. In various embodiments, EDA sensor  310 F can be an externally wearable photoplethysmography (PPG) sensor or an implantable device to be positioned adjacent to an artery and capable of detecting pulsatile information from the artery to compute the BVP signal. Examples of that artery include common iliac artery, internal iliac artery, gonadal artery, inferior mesenteric artery, inferior rectal artery, inferior gluteal artery, superior gluteal artery, renal artery, and femoral artery. Examples of BVP sensor  310 G as an implantable device can include a photoplethysmography (PPG) sensor to detect the pulsatile information (including timing, shape, and morphology) by passing light through the artery, an electrical bioimpedance or impedance cardiography sensor to detect the pulsatile information (including timing, shape, and morphology) by measuring change in impedance across artery as blood flow changes, an accelerometer to detect the pulsatile information (including timing, shape, and morphology) by measuring changes in position as shape of the artery changes during blood flow, a pressure sensor to be positioned around the artery to detect the pulsatile information the pulsatile information (including timing, shape, and morphology) by directly measuring pressure from the artery, and a pressure sensor to be positioned inside the artery to detect the pulsatile information (including timing, shape, and morphology) by directly measuring pressure within the artery. In various embodiments, BVP sensor  310 G can include any one or any combination of these examples. 
     Impedance sensor  310 H can sense a bioelectric impedance. In various embodiments, impedance sensor  310 H can be an externally wearable device to measure skin impedance (e.g., allowing for measurement of heart rate) or an implantable device (e.g., allowing for measurement of respiration rate). 
     Sleep signal sensing circuit  312  can process the one or more sleep signals sensed by sleep sensor(s)  310 , such as by filtering and/or amplifying each sensed sleep signal. Sleep parameter generator  314  can generate one or more sleep parameters corresponding to the sleep state of the patient using the processed one or more sleep signals. The structure and functional capability of sleep signal sensing circuit  312  and sleep parameter generator  314  depend on which sleep sensor(s) are included in sleep sensor(s)  310 . In various embodiments, the one or more sleep parameters have one or more values, when used individually or in combination, that can indicate the patient&#39;s sleep state. 
     Sleep analyzer  316  represents an example of sleep analyzer  216  and can determine the sleep state of the patient using the one or more sleep parameters generated by sleep parameter generator  314 . Sleep analyzer  316  analyzer  316  can include a sleep parameter analyzer (or sleep parameter analyzer circuit)  318  and a sleep score generator (or sleep score generator circuit)  320 . Sleep parameter analyzer  318  can receive and analyze the one or more sleep parameters. In one embodiment, the one or more sleep parameters have values indicative of the patient&#39;s sleep stages. For example, the values of the one or more sleep parameters can be mapped to the sleep stages using data collected from the patient or collected from a patient population. Sleep stage can be classified as, but not being limited to, awake, slow-wave sleep, REM sleep, non-REM1 sleep, or non-REM2. Analysis of the one or more sleep parameters can result in the current sleep stage of the patient as well as time and/or percentage of time spent in each sleep stage. Sleep score generator  320  can compute a sleep score indicative of sleep stage or quality using an outcome of the analysis of the one or more sleep parameters. For example, value ranges each corresponding to one of sleep stages may be determined for each of the one or more sleep parameters for the patient, and used for computing the sleep score as a function of the sleep stage. In various embodiments, the sleep score can include a number (numerical value), a sleep signal metric, and/or a number being a function of the sleep signal metric. 
     In one embodiment, sleep parameter analyzer  318  produces a sleep signal metric using the one or more sleep parameters. The sleep signal metric can be a linear or nonlinear combination of multiple sleep parameters. In one embodiment, sleep parameter analyzer  318  produces the sleep signal metric using the multiple sleep parameters with the weighting factors each applied to one of these parameters. In one embodiment, sleep parameter analyzer  318  adjusts the weighting factors through automatic learning and adaptation to the patient over time (e.g., based on stored parameters and/or outcomes of analysis, such as features extracted from the parameters). In another embodiment, sleep parameter analyzer  318  allows the weighting factors to be adjusted manually. In one embodiment, the weighting factors are adjusted according to a calibration schedule or as needed, and the adjustment can be performed by a user such as a physician or other authorized care provider in a clinic, or initiated by the patient and performed by the sleep parameter analyzer automatically at home. In one embodiment, the weighting factors can be patient-specific and dynamically changed based on the patient&#39;s conditions and/or activities, such as the pathological condition(s) for which the patient is treated, physical condition, time of day, and/or physical activity. In one embodiment, sleep score generator  320  computes the sleep score using the sleep signal metric. In one embodiment, pain score generator  320  trends the sleep signal metric and computes the sleep score using the resulting trending of the sleep signal metric. 
       FIG. 4  illustrates an embodiment of a pain management system  400 , which represent an example of therapy system  100 . Pain management system  400  can include sleep monitoring circuit  102  (including its various embodiments as discussed for sleep monitoring circuit  202  and  302 ), a control circuit  404 , and a pain relief device  406 . 
     Pain relief device  406  can deliver one or more pain relief therapies for treating chronic pain and/or symptoms associated with the chronic pain. In various embodiments, pain relief device  406  can include a neurostimulator (also referred to as neuromodulator) to deliver neurostimulation (also referred to as neuromodulation) to neural tissue such as the spinal cord, brain, and peripheral nerves or a drug pump to delivery drug into the body locally, such as in the intrathecal space. In one embodiment, the neurostimulator includes a pulse generator to generate and deliver electrical stimulation pulses. In other embodiments, the neurostimulator can deliver neurostimulation that uses any form of stimulation energy or agent as stimuli that is capable of modulating neural activities and/or properties. 
     In various embodiments, pain relief device  406  can deliver any one or any combination of spinal cord stimulation (SCS), dorsal root ganglia (DRG) stimulation, deep brain stimulation (DBS), motor cortex stimulation (MCS), transcranial direct current stimulation (tDCS), transcutaneous spinal direct current stimulation (tsDCS), trigeminal nerve stimulation, occipital nerve stimulation, vagus nerve stimulation (VNS), sacral nerve stimulation, pudendal nerve stimulation, sphenopalatine ganglion stimulation, sympathetic nerve modulation, multifidus muscle stimulation, adrenal gland modulation, carotid baroreceptor stimulation, transcutaneous electrical nerve stimulation (TENS), transcranial magnetic stimulation (TMS), tibial nerve stimulation, transcranial magnetic stimulation (TMS), radiofrequency ablation (RFA), pulsed radiofrequency ablation, ultrasound therapy, high-intensity focused ultrasound (HIFU), optical stimulation, optogenetic therapy, magnetic stimulation, other peripheral tissue stimulation therapies, other peripheral tissue denervation therapies, drug therapy (such as delivered from a drug pump), and nerve blocks or injections (such as pharmaceuticals or biologics). 
     Control circuit  404  can control the delivery of the one or more pain relief therapies using therapy parameters and can adjust the therapy parameters based on the sleep state, such as indicated by the pain score or pain signal metric, such that the delivery of the one or more pain relief therapies is adjusted in a way reflecting changes in the sleep state. When pain relief device  106  delivers the neurostimulation, control circuit  404  can control the delivery of the neurostimulation using stimulation parameters and can adjust the stimulation parameters based on the sleep state. In various embodiments, control circuit  404  can optimize the stimulation parameters for the determined sleep state. In various embodiments, control circuit  404  can execute a closed-loop neurostimulation algorithm for treating chronic pain or a disorder related to the chronic pain using the determined sleep state as an input. 
       FIG. 5  illustrates an embodiment of pain management system  500 , which represent another example of therapy system  100 . Pain management system  500  can include sleep monitoring circuit  102  (including its various embodiments as discussed for sleep monitoring circuit  202  and  302 ), a pain monitoring circuit  530 , a control circuit  504 , and pain relief device  406 . 
     Pain monitoring circuit  530  can sense one or more pain signals from the patient and produce a measure of pain of the patient using the one or more pain-related physiological signals. The one or more pain signals can include one or more physiological signals corresponding to the pain of the patient. In one embodiment, the measure of pain includes a pain score quantitatively indicative of a degree of the pain. 
     Control circuit  504  can control the delivery of the one or more pain relief therapies from pain relief device  406  using therapy parameters and can adjust the therapy parameters based on the sleep state determined by sleep monitoring circuit  102  and the measure of the pain produced by pain monitoring circuit  530 . In one embodiment, control circuit  504  can adjust the therapy parameters based on the sleep score and the pain score. This can be achieved by, for example, producing the pain score using the sleep score as an input, and adjusting the therapy parameters using the pain score. In one embodiment, control circuit  504  can control the delivery of the one or more pain relief therapies using the therapy parameters and can adjust the therapy parameters using the pain score (which is a function of the sleep score). In one embodiment, control circuit  504  can optimize the stimulation parameters for the determined sleep state. In various embodiments, control circuit  504  can execute a closed-loop therapy algorithm for treating chronic pain or a disorder related to the chronic pain using the pain score (which is a function of the sleep score) as an input. 
       FIG. 6  illustrates an embodiment of a pain monitoring circuit  630 , which represents an example of pain management circuit  530 . In the illustrated embodiment, pain monitoring circuit  630  can determine the measure of pain, such as the pain score, using the sleep state, such as the sleep score, as discussed in this document, as well as one or more physiological parameters each indicative of a physiological function or physiological state of a patient that is related to pain, one or more functional parameters each indicative of a physical activity or physical state of the patient that is related to pain, and one or more patient parameters related to the pain, such as a parameter representative of intensity of the pain specified by the patient. In various embodiments, pain monitoring circuit  630  can determine the pain score using the sleep score and at least one of a physiological parameter, a functional parameter, or a patient parameter. In some embodiments, pain monitoring circuit  630  can determine the pain score using the sleep score and at least a physiological parameter and a functional parameter. 
     In the illustrated embodiment, pain monitoring circuit  630  includes one or more physiological signal sensors  632 , a physiological signal sensing circuit  634 , a physiological parameter generator (or physiological parameter generator circuit)  636 , one or more functional signal sensors  638 , a functional signal sensing circuit  640 , a functional parameter generator (or functional parameter generator circuit)  642 , a patient information input device  644 , a patient information processing circuit  646 , a patient parameter generator (or patient parameter generator circuit)  648 , and a pain analyzer (or pain analyzer circuit)  650 . In various embodiments, pain monitoring circuit  630  can include at least one or more physiological signal sensors  632 , physiological signal sensing circuit  634 , physiological parameter generator  636 , one or more functional signal sensors  638 , functional signal sensing circuit  640 , functional parameter generator  642 , and pain analyzer  650 . 
     In various embodiments, one or more physiological signal sensors  632  can each sense one or more physiological signals, and can each he a non-invasive, percutaneous, or implantable sensor. Physiological signal sensing circuit  634  can process the one or more physiological signals. Physiological parameter generator  636  can generate the one or more physiological parameters using the processed one or more physiological signals. In various embodiments, one or more functional signal sensors  638  can sense one or more functional signals, and can each be a non-invasive, percutaneous, or implantable sensor. Functional signal sensing circuit  640  can process the one or more functional signals. Functional parameter generator  642  can generate the one or more functional parameters using the processed one or more functional signals. In various embodiments, patient information input device  644  can receive patient information related to pain. Patient information processing circuit  646  can process the patient information. Patient parameter generator  648  can generate one or more patient parameters using the processed patient information. Examples of the one or more physiological parameters, the one or more functional parameters, and the one or more patient parameters are discussed in U.S. Provisional Patent Application Ser. No. 62/400,336, entitled “METHOD AND APPARATUS FOR PAIN MANAGEMENT USING OBJECTIVE PAIN MEASURE”, filed on Sep. 27, 2016, assigned to Boston Scientific Neuromodulation Corporation, which is incorporated herein by reference in its entirety. 
     Pain analyzer  630  can receive the one or more physiological parameters from physiological parameter generator  636 , the one or more functional parameters from functional parameter generator  642 , and/or the one or more patient parameters from patient parameter generator  648 , and also receive the sleep score from sleep monitoring circuit  102 . Pain analyzer  630  can analyze the received parameters including the sleep score and computes the pain score using an outcome of the analysis. The pain score indicates a degree of the pain. In one embodiment, pain analyzer  650  produces a signal metric using the received parameters, and computes the composite pain score using the signal metric. In one embodiment, pain analyzer  650  trends the signal metric and computes the composite pain score based on the resulting trending of the signal metric. The signal metric can be a linear or nonlinear combination of the sleep score and the one or more physiological parameters, the one or more functional parameters, and/or the one or more patient parameters. In one embodiment, pan analyzer  650  produces the signal metric using the received parameters with the weighting factors each applied to one of these parameters. In various embodiments, pan analyzer  650  adjusts the weighting factors through automatic learning and adaptation to the patient over time, and/or allows the weighting factors to be adjusted manually. In one embodiment, the weighting factors can be adjusted according to a calibration schedule or as needed, and the adjustment can be performed by the user. In various embodiments, the weighting factors can he patient-specific and dynamically changed based on the patient&#39;s conditions and/or activities. 
       FIG. 7  illustrates an embodiment of a pain management system  700 , such as one in which pain management system  400  or  500  may be implemented, and portions of an environment in which pain management system  700  may be used. Pain management system  700  can include an implantable medical device  760 , an implantable lead or lead system  762  connected to implantable medical device  760 , an external device  780  communicatively coupled to implantable medical device  760  via a wireless communication link  782 , a sensor  766  communicatively coupled to implantable medical device  760  via a wireless communication link  768 , a sensor  770  communicatively coupled to implantable medical device  760  via a wireless communication link  772 , and sensor  774  communicatively coupled to implantable medical device  760  via a wireless communication link  776 . A pain monitoring circuit such as pain monitoring circuit  530  or  630  can be contained within implantable medical device  760  or distributed in implantable medical device  760  and external device  780 . Implantable medical device  760  can include a therapy device such as pain relief device  406  to deliver one or more pain relief therapies. In various embodiments, external device  780  can be implemented as a dedicated device or in a generic device such as a smartphone, a laptop computer, or a tablet computer. 
     In the illustrated embodiment, lead or lead system  762  includes an electrode or electrode array  764 . In various embodiments, additional one or more electrodes can be incorporated onto implantable medical device  760 . In the illustrated embodiment, sensor  766  can include an EEG sensor such as EEG sensor  310 D, sensor  770  can include an ECG sensor such as ECG sensor  310 C, and sensor  774  can include an FDA sensor such as EDA sensor  310 F. Sensors  766 ,  770 , and  774  can each be an implantable sensor or an externally wearable sensor. In various embodiments, the sleep score and the pain score can be produced by implantable medical device  760  using signals sensed by sensors  766 ,  770 , and  774 . 
     The sizes and shapes of the elements of pain management system  700  and their locations relative to the patient&#39;s body are illustrated by way of example and not by way of restriction. Pain management system  700  is discussed as a specific application of pain management according to various embodiments of the present subject matter. In various embodiments, the present subject matter may be applied in any type of pain management in controlling delivery of one or more pain relief energy and/or agents from an implantable or externally wearable medical device. 
       FIG. 8  illustrates an embodiment of a method  800  for pain management. In various embodiments, pain management system  400 ,  500 , or  700  can be configured to perform method  800 . 
     At  802 , one or more sleep signals are sensed from the patient. The one or more sleep signals can include one or more physiological signals corresponding to the sleep state of the patient. In various embodiments, the one or more sleep signals can each be sensed using a sensor implanted in the patient or a sensor externally worn by the patient. In various embodiments, the one or more sleep signals can each be sensed using a sensor incorporated into a medical device that delivers a pain relief therapy or a sensor communicatively coupled to the medical device via a wireless link. Examples for the one or more sleep signals include an accelerometer signal, a gyroscope signal, an electrocardiogram (ECG) signal, an electroencephalogram (EEG) signal, a temperature signal of the one or more sleep signals, an electrodermal activity (EDA) signal, and a blood volume pulse (BVP) signal, as discussed with reference to  FIG. 3 . 
     At  804 , a sleep state of the patient is determined using the one or more sleep signals. In one embodiment, the sleep state can be awake or a sleep stage identified from predefined sleep stages. There are different ways to define sleep stages. In one example, the sleep stages include non-REM sleep stages 1-4 and REM sleep. In another example, the sleep stages include non-REM sleep stages 1-3 and REM sleep. In yet another example, the sleep stages include slow-wave sleep, REM sleep, non-REM1 sleep, or non-REM2. The present subject matter applies regardless of how sleep stages are defined. In various embodiments, a sleep score representing the sleep state is produced using the one or more sleep signals. The sleep score can indicate the sleep stage, and can include a number, a sleep signal metric, or a number being a function of the sleep signal metric. In various embodiments, in addition to the steep state (e.g., the sleep score), one or more physiological parameters each indicative of a physiological function or physiological state of the patient, one or more functional parameters each indicative of a physical activity or physical state of the patient, and/or one or more patient parameters each including subjective information provided by the patient are received and analyzed to compute a pain score. The pain score can indicate a degree of the pain of the patient. 
     At  806 , whether the sleep score and/or the pain score indicate a need for therapy adjustment is determined. If the sleep score and/or the pain score indicate a need for the therapy adjustment, one or more therapy parameters are adjusted using the sleep score and/or the pain score at  808 , and a pain relief therapy is delivered as controlled using a plurality of therapy parameters including the adjusted one or more therapy parameters at  810 . If the sleep score and/or the pain score do not indicate a need for the therapy adjustment, the pain relief therapy is delivered at  810  without adjusting the one or more therapy parameters. In one embodiment, only the pain score is directly used to indicate the need for therapy adjustment because the pain score is determined as a function of the sleep score. Examples of the pain relief therapy include those deliverable from pain relief device  406 , as discussed with reference to  FIG. 4 . 
     It is to be understood that the above detailed description is intended to be illustrative, and not restrictive. Other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.