Figure 4.

Sleep-wake patterns aligned with the circadian rhythm increase CSS and reduce daytime sleepiness

(A and B) Model simulations of three 6-h sleep episodes across three days regardless of sleep onset time (fixed sleep; A) and three sleep episodes with durations adjusted according to the circadian phase of sleep onset (circadian sleep; B). Although these two sleep-wake patterns have the same TST, two circadian insufficient sleeps (denoted as I) occur with the fixed sleep (A), but only circadian sufficient sleeps (denoted as S) occur with the circadian sleep (B). As a result, time awake in the potential wake region (patterned bars) is longer in the circadian sleep simulation (B) than in the fixed sleep simulation (A).

(C) Quantification of the time awake in the potential wake region.

(D and E) Alignment of sleep-wake patterns with the circadian rhythm of shift workers having similar TST (6-7 h) from SMC data (D and E; $n=9$). The group without EDS (ESS≤10; blue dots; $n=5$) show a much stronger negative dependence of sleep duration on the sleep onset time, compared with the group with EDS (ESS>10; red dots; $n=4$). The number of analyzed main sleep episodes which were the longest sleep episodes of each day (noon-to-noon) were 45 (D) and 36 (E), respectively. The line represents the least-square fitting line with the slope of $\alpha$. $\rho$ and P denote the Spearman's rank correlation coefficient and p value of Spearman's rank correlation test, respectively.

See also Figure S7.