pyActigraphy.io.BaseRaw.CK

BaseRaw.CK(settings='30sec_max_non_overlap', threshold=1.0, rescoring=True)

Cole&Kripke algorithm for sleep-wake identification.

Algorithm for automatic sleep scoring based on wrist activity, developped by Cole, Kripke et al [1].

Parameters

  • settings (str, optional) –

    Data reduction settings for which the optimal parameters have been derived. Available settings are:

    • ”mean”: mean activity per minute

    • ”10sec_max_overlap”: maximum 10-second overlapping epoch per minute

    • ”10sec_max_non_overlap”: maximum 10-second nonoverlapping epoch per minute

    • ”30sec_max_non_overlap”: maximum 30-second nonoverlapping epoch per minute

    Default is “30sec_max_non_overlap”.

  • threshold (float, optional) – Threshold value for scoring sleep/wake. Default is 1.0.

  • rescoring (bool, optional) – If set to True, Webster’s rescoring rules are applied [2]. Default is True.

Returns

ck – Time series containing the D scores (0: sleep, 1: wake) for each epoch.

Return type

pandas.core.Series

Notes

The output variable D of the CK algorithm is defined in [1] as:

\[D = P*( [W_{-4},\dots,W_{0},\dots,W_{+2}] \cdot [A_{-4},\dots,A_{0},\dots,A_{+2}])\]

with:

  • D < 1 == sleep, D >= 1 == wake;

  • P, scale factor;

  • \(W_{0},W_{-1},W_{+1},\dots\), weighting factors for the present minute, the previous minute, the following minute, etc.;

  • \(A_{0},A_{-1},A_{+1},\dots\), activity scores for the present minute, the previous minute, the following minute, etc.

Warning

This algorithm yields scores with a period of 1 minute. Therefore, the time series returned by the CK function has a 1-min period. In the original paper, this algorithm is validated for devices configured in “zero-crossing mode”.

Webster’s rescoring rules [2]:

  1. After at least 4 minutes scored as wake, the next 1 minute scored as sleep is rescored as wake

  2. After at least 10 minutes scored as wake, the next 3 minutes scored as sleep are rescored as wake;

  3. After at least 15 minutes scored as wake, the next 4 minutes scored as sleep are rescored as wake;

  4. If a period of 6 minutes or less that is scored as sleep is surrounded by at least 15 minutes scored as wake, then rescore to wake;

  5. If a period of 10 minutes or less that is scored as sleep is surrounded by at least 20 minutes scored as wake, then rescore to wake.

References

1(1,2)

Cole, R. J., Kripke, D. F., Gruen, W., Mullaney, D. J., & Gillin, J. C. (1992). Automatic Sleep/Wake Identification From Wrist Activity. Sleep, 15(5), 461–469. http://doi.org/10.1093/sleep/15.5.461

2(1,2)

Webster, J. B., Kripke, D. F., Messin, S., Mullaney, D. J., & Wyborney, G. (1982). An Activity-Based Sleep Monitor System for Ambulatory Use. Sleep, 5(4), 389–399. https://doi.org/10.1093/sleep/5.4.389

Examples