Purpose: The primary objective of this study is to determine how the phases of the menstrual cycle influence the results of polysomnography (PSG).
Methods: Twenty-eight adult subjects who reported regular menstrual periods, last menstrual period (LMP) within 26 days of their PSG, no exogenous hormone use, no history of polycystic ovarian syndrome, and who were scheduled for diagnostic PSG at Boston Medical satisfied inclusion criteria for the study. These subjects were divided into a Follicular Cohort (days 0-13 of the cycle) or Luteal Cohort (days 14-26 of the cycle), and a one-way analysis using a t-test was performed to test the hypothesis that the follicular phase confers protection against obstructive sleep apnea (OSA). A likelihood-ratio chi-square test was also applied to assess for a statistically significant association between menstrual stage and the presence of moderate-to-severe sleep apnea (apnea-hypopnea index (AHI) > 15/h). Thus, the statistical analysis was performed using AHI as both a continuous and a categorical outcome.
Results: The mean AHI for patients in the Follicular Cohort (6.1/h) was significantly lower than the Luteal Cohort (14.3/h, p = 0.033). In the Follicular Cohort, 12% of patients had moderate to severe OSA. In the Luteal Cohort, 46% of patients had moderate to severe OSA (p = 0.045).
Conclusions: Subjects undergoing PSG during the follicular phase have significantly lower AHIs than those in the luteal phase. Thus, the timing of PSG acquisition for regularly menstruating women should be considered when interpreting results.
Keywords: menstrual cycle; obstructive sleep apnea; polysomnography.