System and Method for Assessing Sleep State
Assessing sleep state of an individual. A time series of accelerometer data is obtained from an accelerometer device mounted upon or to the individual. From the time series of accelerometer data a percentage of time in which the individual is substantially immobile (% TA) is determined. From the time series of accelerometer data a typical time of continuous immobility (MTI) is also determined. The % TA and MTI are combined such as by weighted sum, to produce a sleep score. If the sleep score exceeds a threshold, this is an indication that the individual is asleep.
1 . A method of assessing sleep state of an individual, the method comprising:
obtaining a time series of accelerometer data from an accelerometer device mounted upon or to the individual;
determining from the time series of accelerometer data a percentage of time in which the individual is substantially immobile (% TA);
determining from the time series of accelerometer data a typical time of continuous immobility (MTI);
combining the % TA and MTI to produce a sleep score; and
if the sleep score exceeds a threshold, outputting an indication that the individual is asleep.
2 . The method of claim 1 when used in a non-clinical setting such as the individual's home.
3 . The method of claim 1 applied to assess sleep state of Parkinsonian subjects.
4 . The method of claim 1 applied to assess sleep state of non-Parkinsonian subjects.
5 . The method of claim 1 wherein producing the sleep score further comprises summing or otherwise combining 2 or more of a set of sleep-related variables derived from the accelerometer data.
6 . The method of claim 5 wherein the sleep related variables include a variable reflecting the individual's attempts at being active.
7 . The method of claim 5 wherein the sleep related variables include a variable reflecting the individual's inactivity while awake.
8 . The method of claim 5 wherein the sleep related variables include a variable reflecting the individual's immobility while asleep.
9 . The method of claim 5 wherein the sleep related variables include a variable reflecting the individual's sleep duration.
10 . The method of claim 5 wherein the sleep related variables include a variable reflecting the individual's sleep fragment length.
11 . The method of claim 5 wherein the sleep related variables include a variable reflecting the individual's Sleep Quality.
12 . A system for assessing sleep state of an individual, the system comprising:
an accelerometer device configured to be mounted upon or to the individual and configured to obtain a time series of accelerometer data; and
a processor configured to determine from the time series of accelerometer data a percentage of time in which the individual is substantially immobile (% TA), the processor further configured to determine from the time series of accelerometer data a typical time of continuous immobility (MTI); the processor further configured to combine the % TA and MTI to produce a sleep score; and the processor further configured to, if the sleep score exceeds a threshold, output an indication that the individual is asleep.
13 . A non-transitory computer readable medium for assessing sleep state of an individual, comprising instructions which, when executed by one or more processors, causes performance of the following:
obtaining a time series of accelerometer data from an accelerometer device mounted upon or to the individual;
determining from the time series of accelerometer data a percentage of time in which the individual is immobile (% TA);
determining from the time series of accelerometer data a median or typical time of continuous immobility (MTI);
combining the % TA and MTI to produce a sleep score; and
if the sleep score exceeds a threshold, outputting an indication that the individual is asleep.