@Article{Mason2026,
journal="Biology of Sport",
issn="0860-021X",
year="2026",
title="Objective sleep characteristics of elite academy soccer players: 
a seven-day actigraphy analysis of a U15 national league squad",
abstract="This study quantified objective sleep characteristics in elite academy soccer players using actigraphy and determined how day type (training days, non-training days, and competition days) influences sleep parameters. Objective sleep characteristics of elite academy soccer players (n = 13) were analysed across training days (TD), non-training days (NTD), and competition days (CD) using 7-day actigraphy monitoring. Significant differences were found between day types for total sleep time (TST) (χ²(2) = 8.59, p = 0.01, η² = 0.09) and time in bed (TIB) (χ²(2) = 9.27, p = 0.01, η² = 0.10). Training days yielded substantially lower values (TST: 431 ± 95.2 min; TIB: 478 ± 100 min) compared to non-training days (TST: 541 ± 231 min; TIB: 596 ± 240 min), representing mean differences of 110 minutes (95% CI: 39–181 min) for TST and 118 minutes (95% CI: 44–192 min) for TIB. No significant differences were found for sleep onset latency (SOL: 19.3 ± 19.6 min), number of awakenings (NoA: 39.8 ± 14.5), wake after sleep onset (WASO: 53.3 ± 25.8 min), or sleep efficiency (%SE: 84.4 ± 5.97%) (all p > 0.05). Critically, while TST and %SE met age-specific recommendations, NoA and WASO substantially exceeded thresholds for good sleep quality. Despite adequate sleep duration, elevated WASO and NoA indicate compromised sleep quality through fragmentation. These findings highlight the necessity for comprehensive sleep monitoring in elite adolescent athletes extending beyond duration alone. Future research should investigate targeted interventions addressing sleep fragmentation within the constraints of training, competition, and academic schedules.",
author="Mason, Lorcán
and Connolly, James
and Devenney, Lydia
and Lacey, Karl
and Faulkner, Maria
and Doherty, Rónán",
pages="999--1008",
doi="10.5114/biolsport.2026.158301",
url="http://dx.doi.org/10.5114/biolsport.2026.158301"
}