apply_sadeh: Apply the Sadeh algorithm

In oslerinhealth/actigraph.sleepr: Detect Periods of Sleep and Non-Wear from 'ActiGraph' Data

Description

The Sadeh sleep scoring algorithm is primarily used for younger adolescents as the supporting research was performed on children and young adults.

Usage

apply_sadeh(agdb)

Arguments

agdb	A tibble (tbl) of activity data (at least) an epochlength attribute. The epoch length must be 60 seconds.

Details

The Sadeh algorithm requires that the activity data is in 60s epochs and uses an 11-minute window that includes the five previous and five future epochs. This function implements the algorithm as described in the ActiGraph user manual.

The Sadeh algorithm uses the y-axis (axis 1) counts; epoch counts over 300 are set to 300. The sleep index (SI) is defined as

SI = 7.601 - (0.065 * AVG) - (1.08 * NATS) - (0.056 * SD) - (0.703 * LG)

where at epoch t

AVG

the arithmetic mean (average) of the activity counts in an 11-epoch window centered at t

NATS

the number of epochs in this 11-epoch window which have counts >= 50 and < 100

SD

the standard deviation of the counts in a 6-epoch window that includes t and the five preceding epochs

LG

the natural (base e) logarithm of the activity at epoch t. To avoid taking the log of 0, we add 1 to the count.

The time series of activity counts is padded with zeros as necessary, at the beginning and at the end, to compute the three functions AVG, SD, NATS within a rolling window.

Finally, the sleep state is asleep (S) if the sleep index SI is greater than -4; otherwise the sleep state is awake (W).

Value

A tibble (tbl) of activity data. A new column sleep indicates whether each 60s epoch is scored as asleep (S) or awake (W).

References

A Sadeh, KM Sharkey and MA Carskadon. Activity based sleep-wake identification: An empirical test of methodological issues. Sleep, 17(3):201–207, 1994.

ActiLife 6 User's Manual by the ActiGraph Software Department. 04/03/2012.

See Also

collapse_epochs, apply_cole_kripke, apply_tudor_locke

Examples

library("dplyr")
data("gtxplus1day")

gtxplus1day %>%
  collapse_epochs(60) %>%
  apply_sadeh()

oslerinhealth/actigraph.sleepr documentation built on May 25, 2021, 1:06 p.m.