HEART RATE VARIABILITY WITH SLEEP DETECTION

• US 20160374567A1
• Filed: 06/25/2015
• Published: 12/29/2016
• Est. Priority Date: 06/25/2015
• Status: Active Grant

• Current Assignee: Whoop, Inc.
• Original Assignee: Whoop, Inc.
• Inventors: Breslow, Emily Rachel, Capodilupo, John, Ahmed, William
• Granted Patent: US 9,743,848 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0204 of power management
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0533 Measuring galvanic skin response
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/4809 Sleep detection, i.e. determining whether a subject is asleep or not
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A system uses continuous tracking of sleep activity and heart rate activity to evaluate heart rate variability immediately before transitioning to an awake state, e.g., at the end of the last phase of deep sleep. In particular, a wearable, continuous physiological monitoring system as described herein includes one or more sensors to detect sleep states, the transitions between sleep states, and the transitions from a sleep state to an awake state for a user. This information can be used in conjunction with continuously monitored heart rate data to calculate heart rate variability of the user at the end of the last phase of sleep preceding the user waking up. By using the history of heart rate data in conjunction with sleep activity in this manner, an accurate and consistent recovery score can be calculated based on heart rate variability.

Claims

1. A method of operating a wearable, continuous physiological monitoring system comprising:

detecting a sleep state of a user;

monitoring a heart rate of the user substantially continuously with the continuous physiological monitoring system;

recording the heart rate as heart rate data;

detecting a waking event at a transition from the sleep state of the user to an awake state;

calculating a heart rate variability of the user at a moment in a last phase of sleep preceding the waking event based upon the heart rate data; and

calculating a recovery score for the user based upon the heart rate variability from the last phase of sleep.

2. The method of claim 1 further comprising calculating additional recovery scores after one or more other waking events of the user for comparison to the recovery score.

3. The method of claim 1 further calculating a duration of the sleep state and using the duration to calculate the recovery score.

4. The method of claim 1 further comprising detecting the sleep state using an accelerometer of the wearable, continuous physiological monitoring system.

5. The method of claim 4 further comprising detecting the waking event using the accelerometer.

6. The method of claim 1 further comprising detecting a galvanic skin response (GSR) of the user with the wearable, continuous physiological monitoring system and using the GSR to detect the sleep state.

7. The method of claim 1 further comprising detecting at least one of the sleep state and the waking event based upon the heart rate data.

8. The method of claim 1 wherein recording the heart rate data includes recording the heart rate data continuously without calculating the heart rate variability.

9. The method of claim 1 further comprising detecting a slow wave sleep period occurring most recently before the waking event.

10. The method of claim 9 further comprising:

evaluating a quality of heart rate data using a data quality metric for the slow wave sleep period; and

calculating the heart rate variability for a window of predetermined duration within the slow wave sleep period having a highest quality of heart rate data according to the data quality metric.

11. The method of claim 1 wherein the wearable, continuous physiological monitoring system includes a processor, one or more light emitting diodes, and one or more light detectors configured to obtain the heart rate data from the user.

12. The method of claim 1 further comprising calculating a sleep need score estimating an amount of sleep needed by the user in a next night, and communicating the sleep need score to user.

13. A system comprising:

a wearable housing;

one or more sensors in the wearable housing; and

a processor in the wearable housing, the processor configured to operate the one or more sensors to detect a sleep state of a user wearing the wearable housing, to monitor a heart rate of the user substantially continuously, to record the heart rate as heart rate data without calculating a heart rate variability for the user, to detect a waking event at a transition from the sleep state of the user to an awake state, to calculate the heart rate variability of the user at a moment in a last phase of sleep preceding the waking event based upon the heart rate data, and to calculate a recovery score for the user based upon the heart rate variability from the last phase of sleep.

14. The system of claim 13 wherein the one or more sensors include a light detector configured to provide data to the processor for calculating the heart rate variability.

15. The system of claim 13 wherein the one or more sensors include an accelerometer configured to provide data to the processor for detecting the sleep state or the waking event.

16. The system of claim 13 further comprising a light source coupled to the housing and controlled by the processor, the light source directed toward a skin on an appendage of the user.

17. The system of claim 13 wherein the one or more sensors measure a galvanic skin response of the user.

18. A computer program product for operating a wearable, continuous physiological monitoring system, the computer program product comprising computer executable code embodied in a non-transitory computer readable medium that, when executing on the wearable, continuous physiological monitoring system, performs the steps of:

detecting a sleep state of a user;

monitoring a heart rate of the user substantially continuously with the continuous physiological monitoring system;

recording the heart rate as heart rate data;

detecting a waking event at a transition from the sleep state of the user to an awake state;

calculating a heart rate variability of the user at a moment in a last phase of sleep preceding the waking event based upon the heart rate data; and

calculating a recovery score for the user based upon the heart rate variability from the last phase of sleep.

19. The computer program product of claim 18 further comprising code that performs the step of calculating a duration of the sleep state and using the duration to calculate the recovery score.

20. The computer program product of claim 18 further comprising code that performs the step of detecting at least one of the sleep state and the waking event using an accelerometer of the wearable, continuous physiological monitoring system.