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

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.

Changes in diurnal rhythms of free cortisol secretion during different phases of menstrual cycle / 生理学报

The effect of the menstrual cycle on the diurnal cortisol rhythm was investigated in 15 normally cyclic healthy women during reproductive life. Salivary cortisol was measured by radioimmunoassay in samples collected every 2 h for 24 h during the four phases of the menstrual cycle: menstrual phase, late follicular/peri-ovulation phase, early to mid luteal phase and late luteal phase, respectively. Distinct diurnal rhythms of free cortisol were found throughout the menstrual cycle by using a nonlinear periodic regression model. The model was characterized by an asymmetrically peaked diurnal cycle and ultradian harmonics. There was a trend to higher troughs and significantly shorter peak-width in phase II and phase IV compared to phase I. The ultradian amplitude in phase IV was significantly lower compared with phase I and showed a trend of decrease compared with phase II. The results suggest that the daily cortisol secretion is modulated by the phase of the menstrual cycle.