Table 1. Description of features extracted from each physiological signal as time-series data.

Feature Category	Feature Description
Distribution	• Mode of z-scored distribution (5-bin histogram) • Mode of z-scored distribution (10-bin histogram)
Simple temporal statistics	• Longest period of consecutive values above the mean • Time intervals between successive extreme events above the mean • Time intervals between successive extreme events below the mean
Linear autocorrelation	• First 1/e crossing of the autocorrelation function • First minimum of the autocorrelation function • Total power in the lowest fifth of frequencies in the Fourier power spectrum • Centroid of the Fourier power spectrum • Mean error from a rolling 3-sample mean forecasting
Nonlinear autocorrelation	Time-reversibility statistic, ((xt+1 – xt)3)t • Automutual information, m = 2, τ = 5 • First minimum of the automutual information function
Successive differences	• Proportion of successive differences exceeding 0.04σ • Longest period of successive incremental decreases • Shannon entropy of two successive 3-letter symbolization • Change in correlation length after iterative differencing • Exponential fit to successive distances in 2-d embedding space
Fluctuation analysis	• Proportion of slower timescale fluctuations that scale with DFA (50% sampling) • Proportion of slower timescale fluctuations that scale with linearly rescaled range fits
Others	• Trace of covariance of transition matrix between symbols in 3-letter alphabet • Periodicity measure of Wang et al. [52]