Sink or swim? Sleep in highly trained adolescent swimmers during the in-season phase of training

Abstract

Sleep is vital to the physiological and cognitive functioning in humans, however, disruption to sleep is a growing issue. Requirements of training in high performing adolescent athletes is increasing but it is largely unknown what effect this has upon their sleep. Extra-curricular activities such as sport, music, and part-time work are all contributing factors to the sleep disturbances adolescents’ experience. Until now, limited research has been available on high performing adolescent athletes sleep as most research has focused on sleep in elite adult athletes. Research to date has illustrated that elite adult athletes experience disruptions to their sleep due to training and competitions which subsequently impacts their recovery, performance and fatigue. The few studies to investigate adolescent athletes have found that sleep has significant effects on injury occurrence, academic performance, mental health, and obesity, as discussed in the literature review in the first chapter of this thesis. Furthermore, through the limited previous research, it has been found that adolescent athletes sleep is disrupted on nights preceding early morning training sessions. The second chapter of this thesis includes an original study investigating the sleep of highly trained adolescent swimmers. Fifteen adolescent swimmers volunteered to participate in this study, where their sleep was measured via subjective and objective measures over a two-week ‘normal’ in-season training phase. Participants subjectively recorded their total sleep time (TST), sleep latency (SL), and wake episodes (WE) through a daily sleep diary. In conjunction, objective sleep indices (TST, SL, WE, total time in bed (TTB), wake after sleep onset (WASO), sleep efficiency (SE), sleep onset time (SOT), and wake time (WT) were measured through a wrist actigraph device. Analysis revealed that participants significantly overestimated their sleep duration by approximately one hour per night compared to their objective TST. Furthermore, on evenings preceding early morning training (EARLY), participants TST and TTB was significantly less compared to nights preceding day trainings (DAY) and rest days (REST). Finally, the third chapter of this thesis summarises the overall findings of the thesis, as well as highlighting practical applications, and potential future research directions.