Night-to-night variability of objective sleep outcomes in youth Middle Eastern football players

Objective: To describe components of night-to-night variation in objective measures of sleep. Methods: We conducted a secondary data analysis of consecutive and chronologically ordered actigraphy-based measurements for time in bed (min), time asleep (min), and wake-after-sleep onset (min). This investigation examined 575 individual night-based measures available for a sub-sample of fifty-two, male youth Middle Eastern football players tracked over a 14-day surveillance period (chronological age range: 12.1 to 16 years). Distinct multivariable-adjusted generalized additive models included each objective sleep outcome measure as dependent variable and disaggregated components of variation for night measurement-by-sleep period interaction, week part (weekday or weekend), and study participant random effects from within-subject night-to-night sleep variation. Results: The within-subject standard deviation (SD) of +/- 98 min (95% confidence interval [CI], 92 to 104 min) for time in bed, +/- 87 min (95%CI, 82 to 93 min) for time asleep, and +/- 23 min (95%CI, 22 to 25 min) for wake-aftersleep-onset overwhelmed other sources of variability and accounted for -44% to 53% of the overall night-tonight variation. The night measurement-by-fragmented sleep period interaction SD was +/- 83 min (95%CI, 44 to 156 min) for time in bed, +/- 67 min (95%CI, 34 to 131 min) for time asleep, and +/- 15 min (95%CI, 7 to 32 min) for wake-after-sleep-onset that accounted for -22% to 32% of each sleep outcome measure overall variability. Conclusions: Substantial random night-to-night within-subject variability poses additional challenges for strategies aiming to mitigate problems of insufficient and inconsistent sleep that are detrimental to school learning and youth athlete development processes.