General
This article describes the different parameters in the "Activity & Sleep" algorithm.
SENS motion can, among others, be used to provide an objectve assessment of sleep quality. This is done with the "Activity & Sleep" algorithm, which is based on measuring movement during sleep, sleep quality and sleeping position.
The algorithm is built to find the time where a patient goes to sleep between 6 PM and 1 AM, and the time where a patient wakes up between 5 AM and 12 PM. The algorithm only determines sleep at night, and does not regard naps during the day as sleep. Therefore the algorithm will not work for patients with irregular sleeping schedules.
For a description of the general activity categories, please refer to this article: Description of activity categories
Description of Sleep Parameters
The "Activity & Sleep" algorithm assesses movements during sleep, duration of sleep and sleeping position. The following table describes the different parameters.
The categorization of movement relies on "intensity count". Read more about intensity count in this article: Description of activity categories
Bold: categories as seen on the web-app (app.sens.dk)
Italics: categories as seen on an exported CSV-file
| Duration of sleep |
Estimates when the patient sleeps (time between going to sleep and waking up). The patient is estimated to have gone to bed the last time the patient is up and walking for more than 1 minute between 6 PM and 1 AM. The patient is estimated to have woken up the first time the patient is up and walking for more than 30 seconds between 5 AM and 12 PM. |
|
Sleep No Movement sleep_no_movement |
The patient lies horizontally (+- 45 degrees) without movement. Movements with intensity count under 2 are also categorized as Sleep No Movement. |
|
Sleep Movement sleep_movement |
The patient lies horizontally (+- 45 degrees) with minimal to moderate movements. Movements with an intensity count over 2 is categorized as Sleep Movement. The movement is quantified with +30 seconds before and after the movement. For instance, a movement lasting 10 seconds will be assigned this category with +30 seconds before and after the movement. This means a total of 1 minute and 10 seconds categorized as Sleep Movement. Note that movements in this category usually happen during light sleep. |
|
Sleep Active sleep_active |
The patient is standing vertically (+- 45 degrees). The movement is categorized as Sleep Active regardless of whether the patient is moving or not, as long as the patient is standing upright. |
The information above is based on these references:
J. B. Webster et al. An Activity Based Sleep Monitor System for Ambulatory Use.
J. D. van der Berg et al. Identifying waking time in 24 h accelerometry data in adults using an automated Algorithm.
Input from Professor Poul Jennum from Glostrup Hospital
Below you see an example of the "Activity & Sleep" algorithm applied on a real measurement.
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