Author(s): GOLDBERG, M., DEBARNOT, U., Institution: UNIVERSITÉ LYON 1, Country: FRANCE, Abstract-ID: 566

INTRODUCTION:
While sleep quantity and quality are well-established indicators of sleep health, sleep variability is increasingly recognized as an additional key dimension, commonly assessed using the Coefficients of Variation (CV) or recently evaluated with the Sleep Regularity Index (SRI).1 However, these metrics capture distinct aspects of variability,2 with CV reflecting overall night-to-night variability (values >10% indicating high variability) and SRI quantifying the consistency of sleep-wake patterns across nights, with a mean score of 81.0 reported in the general population.3 Athletes, particularly those involved in team sports with collectively scheduled training sessions, are frequently exposed to irregular sleep patterns,4,5 and differences in sleep variability according to sex and competitive level remain insufficiently characterized. Given the central role of sleep in recovery, sleep education promoting stable sleep behaviours may be essential to enhance sleep regularity. Therefore, this study aimed to compare sleep variability in male and female team-sport athletes competing at professional and recreational levels and evaluate the effects of sleep education including recommendations to maintain regular sleep-wake schedule on CV and SRI.
METHODS:
Sixty-five team-sport athletes (36 professional males [Tier 3], 29 recreational females [Tier 2]) practicing rugby and handball were monitored over two weeks (PRE/POST), separated by one month, using actigraphy and daily subjective sleep questionnaires. Before the POST week, athletes received individualized sleep recommendations to align sleep schedules with their own chronotype by establishing consistent bed and wake-up times. Comparisons between male and female metrics were conducted with Mann-Whitney U tests. As residuals did not follow normality, nonparametric ANOVA-Type Statistic models were applied to assess the main effects of sex and phase.
RESULTS:
While CVwake-up time was 17.7 ± 5.6 for females, 13.2 ± 4.9 for males and decreased for both sexes following the intervention (13.3 ± 6.2, 10.5 ± 3.6 respectively; p < 0.001, η2 = 0.20), no other variables exhibited significant changes. Median SRI was 72.0 in PRE and 73.4 in POST, but no statistical difference was observed. Whatever the week, SRI was positively correlated with sleep efficiency. Compared to males, females showed higher variability in CVbedtime and CVwake-up time (p = 0.04, η2 = 0.09 for both) in both weeks.
CONCLUSION:
Athletes showed high overall and consecutive sleep variability, confirming previous studies,4,5 and for the first time, sleep education improved sleep timing consistency in both sexes. While CV offer a useful and accessible overview of sleep timing, the SRI gives a validated score capturing night-to-night consistency. CV and SRI provide complementary insights into sleep variability and may inform future sleep strategies to improve athletes sleep health.
1Kemp et al., 2023 2Fischer al., 2021 3Windred et al., 2021 4Wilson et al., 2025 5Halson et al., 2022