Author(s): PAICE, C., HALSON, S., JOHNSTON, R., RUSSELL, S., WATTS, D., Institution: AUSTRALIAN CATHOLIC UNIVERSITY, Country: AUSTRALIA, Abstract-ID: 2737

INTRODUCTION:
Menstrual dysfunction is more prevalent in elite female athletes compared to the general population. Sleep is critical to athletic performance, yet the impact of menstrual dysfunction on sleep remains poorly understood. This study investigated sleep quantity and quality by, comparing those classified with menstrual dysfunction to healthy natural menstruating female athletes.
METHODS:
Elite female athletes (n=71; age 23 ± 6.5 years) classified as Tier 3 (Highly Trained), Tier 4 Elite/International) and Tier 5 (World Class) athletes were monitored for two cycles, or equivalent timeframes for Hormonal Contraceptive (HC) users. The Pittsburgh Sleep Quality Index (PSQI) evaluated initial sleep quality. Objective sleep data was collected throughout the observation period using the Oura Ring Gen3. A sleep diary and menstrual symptom survey was completed in the morning by athletes daily. Venous blood samples were collected at Phases 1, 3, and 4 in naturally menstruating participants to capture distinct hormonal profiles and confirm cycle phases, with corresponding timepoints chosen for HC users.
RESULTS:
Following two monitored menstrual cycles, athletes were categorised into five groups: HC users, naturally menstruating – ovulation determined (NM-Ov), naturally menstruating – without determined ovulation (NM-Anov), abnormal uterine bleeding (AUB), and ovarian dysfunction (OD). Although 66% of participants were classified as “poor sleepers” based on the initial PSQI, objective measures (Oura Ring) of total sleep duration indicated that all groups obtained between 7.5 to 7.7 hours. Sleep efficiency was also not different between cohorts, ranging from 89.3% to 90.5%. However, significant intra- and inter-individual variation was observed in deep sleep duration (HC: 82.7 min; NM-Ov: 94.7 min; NM-Anov: 81.2 min; AUB: 97.3 min; OD: 88.8 min). Notably, participants with NM-Anov and AUB demonstrated significant declines in deep sleep duration across cycle days, whereas no systematic cycle-related changes were observed in the NM-Ov or OD groups.
CONCLUSION:
These results highlight the discrepancies between subjective and objective sleep measures in female athletes. Our novel findings suggest that while total sleep duration remains stable across various menstrual statuses, specific menstrual dysfunctions may lead to altered sleep architecture. The substantial individual variation in deep sleep duration highlights that the relationship between menstrual health and sleep is highly individualised. Fluctuations in deep sleep duration may have considerable physiological consequences for elite athletes, as this stage of sleep is critical for physical recovery. Consequently, the impact of menstrual dysfunction on athlete’s sleep warrants individualised assessment to identify athletes experiencing altered sleep architecture and elucidate underlying mechanisms.