Additional file 1. Schematic illustration of the procedure to compute average PSD. (a) An example of a 20-minute segment of data. (b) The 1-min multitaper PSDbetween 4 and 5 minutes. (c) The average PSD multitaper among the 20 1-min multitaper PSD. The number of tapers we applied was 6. The number of points for the FFT algorithm was 4096,the upper power-of-2 length of the 1-min window. Thus, the number of frequency bins between 0.5 and 10 Hz is 974.