Changes in circadian sleep-wake and rest-activity rhythms during different phases of menstrual cycle

The results of previous studies on the menstrual-related sleep changes were inconsistent. The menstrual-related circadian sleep-wake and rest-activity rhythms changes are still uncertain. Using actigraphic monitoring of wrist activity, we investigated the sleep-wake and rest-activity patterns of 12 normally cyclic healthy women during reproductive life. Multivariate analyses were performed during the four phases of the menstrual cycle: menstrual phase (lst to 5th day of menstrual cycle), late follicular/peri-ovulation phase (11th to 15th day), early to mid luteal phase (18th to 23rd day) and late luteal phase (25th to 28th day), respectively. The variables of circadian sleep-wake pattern were similar in the four phases, except an increased tendency of the sleep latency in peri-ovulation phase compared with the early to mid-luteal phase (19+/-18 vs 9+/-6), but unfortunately no statistical significance were found (P<0.10). Concerning the circadian patterning of rest and activity, the interdaily stability (IS) in menstrual phase was significantly higher than the early to mid luteal phase (P<0.05). In early to mid luteal phase, the M10 onset time was significantly earlier compared with that of the late follicular/peri-ovulation phase (P<0.05), and the cosinor peak time was significantly earlier compared with that of the late luteal phase (P<0.05). The circadian periodogram calculated the period length of the rhythm of average woman. The average length was (24.01+/-0.29) h, and there was no significant difference among the four menstrual phases. The results suggest that the phase of circadian rest-activity rhythm may be modulated by the menstrual cycle, but the quantity and quality of the rest-activity rhythm have no essential different, and that menstrual cycle may have no effects on the circadian sleep-wake rhythm in normally cyclic healthy women.