Score actigraphy epochs as wake or sleep using the Cole-Kripke algorithm

Applies the Cole-Kripke algorithm to a vector of zero-crossing mode (ZCM) activity counts, scoring each epoch as wake (1) or sleep (0) using a weighted sum of activity in a surrounding window.

Usage

score_epochs_cole_kripke(
  zcm,
  P = 0.000464,
  weights_before = c(34.5, 133, 529, 375, 408, 400.5, 1074, 2048.5, 2424.5),
  weights_after = c(1920, 149.5, 257.5, 125, 111.5, 120, 69, 40.5)
)

Arguments

zcm

numeric vector of ZCM activity counts, one value per epoch.

P

numeric(1). Scaling factor. Default is 0.000464 (Cole et al., 1992).

weights_before

numeric(9). Weights applied to the 9 epochs before the current epoch. Defaults to the values from Cole et al. (1992), Table 2.

weights_after

numeric(8). Weights applied to the 8 epochs after the current epoch. Defaults to the values from Cole et al. (1992), Table 2.

Value

An integer vector the same length as zcm, with 1 indicating wake and 0 indicating sleep.

Details

Each epoch's score is computed as:

$$D_i = P \sum_{j=1}^{9} W_j^{-} \cdot A_{i-j} + P \sum_{j=1}^{8} W_j^{+} \cdot A_{i+j}$$

where \(A_i\) is the ZCM count at epoch \(i\), \(W^{-}\) and \(W^{+}\) are the before and after weight vectors from Cole et al. (1992), and \(P = 0.000464\). Epochs with \(D_i \ge 1\) are scored as wake.

References

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. doi:10.1093/sleep/15.5.461

Examples

if (FALSE) { # \dontrun{
rec    <- read_acttrust("recordings/P001.txt")
scores <- score_epochs_cole_kripke(rec$ZCMn)
table(scores)  # 0 = sleep, 1 = wake
} # }