A functional linear modeling comparison between the 24-hr sleep-wake pattern of the Hadza and a small scale agricultural society
in Madagascar characterized as nocturnally bi-phasic, segmented sleepers. The Madagascar population showed a pronounced increased
activity after midnight and a pronounced decrease in activity around noon, whereas the Hadza showed continually increased activity from
sleep’s end until noon when activity showed a steady decrease until a prolonged consolidated bout of sleep in early morning. The bottom
panel illustrates the point-wise critical value (dotted line) is the proportion of all permutation F values at each time point at the significance
level of 0.05. When the observed F-statistic (solid line) is above the dotted line, it is concluded the two groups have significantly different
mean circadian activity patterns at those time points [Color figure can be viewed at wileyonlinelibrary.com]