Figure 1. Changes in TIB, TST, SE, and SOL across M1/2 and MF.

(A) TIB varied significantly (P for ANOVA, .005) across the menstrual cycle and was significantly reduced in M2 compared with M1 and MF. Values represent the mean ± standard deviation (SD). (B) TST varied significantly (P for ANOVA, 0.003) across the menstrual cycle and was significantly reduced in M2 compared with MF. Values represent the mean ± SD. (C) SE varied significantly (P for ANOVA, 0.019) across the menstrual cycle and was significantly reduced in M1 compared with MF. Values represent the mean ± SD. (D) SOL varied significantly (P for ANOVA, 0.026) across the menstrual cycle and was significantly reduced in M2 compared with MF. Values represent the median and interquartile range. ANOVA, analysis of variance; M1/2, first and second night after menses onset; MF, midfollicular phase; SE, sleep efficiency; SOL, sleep-onset latency; TIB, time in bed; TST, total sleep time.