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How did ActiGraph develop the automatic sleep-detection algorithm used in CentrePoint to estimate in-bed and out-of-bed times?

Last Updated: Feb 21, 2018 02:42PM CST

Using the Tudor-Locke paper Fully automated waist-worn accelerometer algorithm for detecting children’s sleep period time separate from 24-hour physical activity or sedentary behaviors, we have derived an algorithm to calculate bedtimes automatically.

Comparing Tudor-Locke paper to ActiGraph algorithm





Calculating each epoch as sleep or awake

Combines Sadeh sleep algorithm and inclinometer results to classify each epoch. An epoch is only asleep if BOTH the Sadeh algorithm says the subject is asleep and the inclinometer value is OFF.

Uses Sadeh, Cole-Kripke, or a custom sleep algorithm to classify each epoch as asleep or awake. Ignores inclinometer values.

Wear position of device

Algorithm is based off of waist-worn device.

Not specified.

Age of subject

Developed on fourth-grade schoolchildren.

Not specified.

Bedtime definition

5 consecutive asleep minutes.

Same as Tudor-Locke.

Wake time definition

First 10 consecutive minutes of awake time following a period of sleep.

First 12 consecutive minutes of awake time following a period of sleep. 12 minutes seemed to provide improved results for sample files but might need to be revisited.

Minimum amount of time between bedtime and wake time

Must be at least 160 minutes between in bed and out of bed time.

Same as Tudor-Locke

Multiple sleep periods in a day




Auto Sleep Scoring Flowchart

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