Heart rate variability with sleep detection
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.
1. A method of operating a wearable, continuous physiological monitoring system comprising:
monitoring sleep states of a user over a period of time;
monitoring a heart rate of the user substantially continuously with the wearable, continuous physiological monitoring system over the period of time;
recording heart rate data within the period of time;
detecting, within the period of time, a waking event at a transition from a last sleep state of the user to an awake state;
determining an end of a most recent slow wave sleep state occurring most recently before the waking event
calculating a heart rate variability of the user at the end of the most recent slow wave sleep state 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 end of the most recent slow wave sleep state preceding the waking event, the recovery score indicative of a level of recovery of the user's body and health after a period of physical exertion.
2. The method of claim 1 further comprising calculating a duration of sleep and using the duration to calculate the recovery score.
3. The method of claim 1 wherein monitoring sleep states is based on a signal received from an accelerometer of the wearable, continuous physiological monitoring system.
4. The method of claim 3 wherein detecting the waking event is based on the signal received from the accelerometer.
5. The method of claim 1 wherein at least one of monitoring sleep states and detecting the waking event is based upon the heart rate data.
6. The method of claim 1 wherein recording the heart rate data includes recording the heart rate data continuously without calculating the heart rate variability.
7. 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.
8. 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.
9. A system comprising:
a wearable housing;
one or more sensors in the wearable housing; and
a processor in communication with the one or more sensors, the processor configured to receive data from the one or more sensors to monitor sleep states of a user wearing the wearable housing over a period of time, to monitor a heart rate of the user substantially continuously over the period of time, to detect a waking event at a transition from a last sleep state of the user to an awake state, to determine an end of a most recent slow wave sleep state occurring most recently before the waking event, to calculate heart rate variability of the user at a moment in the most recent slow wave sleep state preceding the waking event based upon the heart rate, and to calculate a recovery score for the user based upon the heart rate variability from the most recent slow wave sleep state preceding the waking event.
10. The system of claim 9 wherein the one or more sensors include a light detector configured to provide heart rate data to the processor for calculating the heart rate variability.
11. The system of claim 10 wherein the processor is configured to detect the waking event based on the data from the light detector.
12. The system of claim 10 wherein the processor is configured to monitor sleep states of the user based on the data from the light detector.
13. The system of claim 9 wherein the one or more sensors include an accelerometer configured to provide data to the processor for at least one of monitoring sleep states and detecting the waking event.
14. The system of claim 9 further comprising a light source coupled to the wearable housing, the light source directed toward a skin on an appendage of the user.
15. The system of claim 9 , wherein the processor is within the wearable housing.
16. A computer program product for determining physical recovery of a user wearing a continuous physiological monitoring device, the computer program product comprising computer executable code embodied in a non-transitory computer readable medium that, when executing on one or more computing devices, performs the steps of:
monitoring sleep states of the user;
monitoring a heart rate of the user substantially continuously;
recording the heart rate as heart rate data;
detecting a waking event at a transition from a last sleep state of the user to an awake state;
determining an end of a most recent slow wave sleep state occurring most recently before the waking event;
calculating a heart rate variability of the user at a moment in the most recent slow wave sleep state preceding the waking event based upon the heart rate; and
calculating a recovery score for the user based upon the heart rate variability from the most recent slow wave sleep state preceding the waking event.
17. The computer program product of claim 16 further comprising code that performs the step of calculating a duration of sleep and using the duration to calculate the recovery score.
18. The computer program product of claim 16 further comprising code that performs the step of monitoring sleep states and detecting the waking event using data received from an accelerometer coupled to the user.
19. The computer program product of claim 16 further comprising code that performs the step of monitoring sleep states using the heart rate data.
20. The computer program product of claim 16 further comprising code that performs the step of detecting the waking event using the heart rate data.