Abstract
Insufficient sleep duration may affect athletic performance and health. Inconsistent sleep pattern also has negative health effects, but studies on athletes' intraindividual sleep variability are scarce. The aim of this research was to compare total sleep time (TST) and variability (TST-variability), wakening after sleep onset, and sleep efficiency, during nights preceding early morning practices with other nights, and to investigate sleep characteristics of nights following a day with early morning only, evening only, or both a morning and an evening session in adolescent swimmers. Wrist-worn accelerometers were used to measure 1 week of sleep in 108 swimmers (mean age 16.1 [2.6]y) in Iceland. Adjusted regression analyses and linear mixed models were used to explore associations of training schedules with TST, TST-variability, wakening after sleep onset, and sleep efficiency. Mean TST was 6:32 (h:min) (±39min) and TST-variability was 63 minutes (±25min). TST decreased and TST-variability increased with more early morning practices. TST preceding early training was 5:36 and 5:06 in <16- and ≥16-year-olds, respectively, shorter than on nights preceding later or no morning training (P < .001). Swimmers have extremely short TST preceding early morning sessions and increased TST-variability with more early morning sessions.
Highlights
According to the National Sleep Foundation, teenagers are recommended to sleep for 8 to 10 hours each night [13]
Adolescent swimmers were found to have short average sleep during a whole week of measurements and significantly shorter total sleep time (TST) on nights preceding early morning training sessions compared with nights when late or no morning training was performed
The results of the current study indicate that adolescent swimmers have shorter sleep duration than nonathletic Icelandic adolescents
Summary
According to the National Sleep Foundation, teenagers are recommended to sleep for 8 to 10 hours each night [13]. Swimming is known to impose hard training loads on athletes from young age with early morning sessions being scheduled for children and young adolescents when training in the evenings is no longer enough to match rivals’ performance [12]. Whitworth-Turner et al [39] reported longer sleep duration but lowered sleep efficiency and increased intraindividual night-to-night variability of sleep in young male soccer players (n = 12) compared with nonathlete controls. The aim of this study was to objectively investigate sleep duration and intraindividual night-to-night variability of sleep duration as well as wakening after sleep onset (WASO) and sleep efficiency in young Icelandic swimmers, to compare those sleep characteristics during nights preceding early morning practices with
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