259 Tracking naturalistic sleep over the menstrual cycle with a wearable in healthy young women

Abstract Introduction A woman’s menstrual cycle is characterized by hormonal changes that might affect sleep and therefore daily functionality. While some studies using self-reports have shown a lower sleep quality in the peri-menstruation phase, objective – in lab – studies have not found significant differences in sleep continuity during the menstrual cycle, but are limited by only a few recordings across the cycle. The aim of this study is to examine changes in sleep during the healthy menstrual cycle using a multi-sensory wearable, allowing continuous, objective, reliable and ecologically valid measurement. Methods 12 healthy young women (28.14 ± 2.33) were monitored using Oura ring – a sleep and activity tracker – during an entire menstrual cycle. Participants also reported mood, readiness, and sleep quality using a diary. Four phases of the menstrual cycle were compared (menstruation, periovulation, mid-luteal, and late-luteal). Ovulation day was determined using a urinary luteinizing hormone test. Results Ovulatory cycles were confirmed by the Oura ring, which showed a significant increase in average nocturnal heart rate and skin temperature during the post-ovulatory luteal phase relative to menstruation and periovulation. Oura ring measures of sleep continuity (Sleep Onset Latency, Wake After Sleep Onset) and self-reported sleep quality did not change across the 4 menstrual phases. We observed a trend for objective sleep duration, which tended to be shorter in the mid-luteal and late-luteal phases. We also observed a small reduction in perceived readiness and mood during these two phases. Conclusion Physiological changes (increase in heart rate and body temperature) in the postovulatory phase of the menstrual cycle are detectable with the Oura ring. Sleep features remain quite stable during the healthy, ovulatory menstrual cycle, apart from a trend for slightly shorter sleep duration in the post-ovulatory phases. In comparison to self-reports, which rely on retrospective memory and might be biased by perception and mood, wearable technologies seem to be a sensitive and informative tool to track sleep and physiological changes during the menstrual cycle. Support (if any) Supported by RF1AG061355 (Baker/Mednick)