Menstrual Cycle Symptoms, But Not Oestrogen or Progesterone Concentrations, Are Associated With Sleep in Female Athletes.

This study investigated the associations between ovarian hormones, symptoms, sleep characteristics and nocturnal physiology in female athletes. Twenty-four National Rugby League Indigenous Women's Academy athletes (naturally cycling: n = 11 and mean age: 21 ± 3 years; hormonal contraception: n = 13 and mean age: 22 ± 3 years) completed a 5-week training camp. During the camp, oestradiol and progesterone concentrations were analysed at three timepoints according to naturally cycling and hormonal contraception groups. Symptoms and subjective sleep were measured daily. Athletes were instructed to wear an Oura ring throughout the camp for sleep and nocturnal heart rate (HR) and HR variability (HRV) measures. Statistical analyses included linear mixed models and Pearson's correlations. Neither objective (Oura ring) nor subjective (survey) sleep characteristics were associated with oestradiol or progesterone concentrations. In the naturally cycling group, a higher number of total symptoms were associated with a longer sleep onset latency (r = 0.88, 95% CI [0.60, 0.97]) and increased light sleep (r = 0.75, 95% CI [0.28, 0.93]). Higher oestradiol concentrations were significantly associated with fewer symptoms (estimate ± SE: -0.007 ± 0.002 symptoms, p = 0.003). Luteal days were associated with higher average nocturnal HR and lower HRV than follicular menstrual cycle days (estimate ± SE: 4 ± 0.57 bpm, p < 0.001; estimate ± SE: -7 ± 2.13 ms, p < 0.001, respectively). Negligible to moderate correlations were observed between sleep and total symptoms experienced by athletes using hormonal contraception. In conclusion, sleep measures were not significantly associated with ovarian hormone concentrations. A higher number of total symptoms were associated with sleep disturbance in naturally cycling athletes. To optimise sleep, female athletes may benefit from monitoring and managing menstrual cycle symptoms.