Sleep is a necessity, vital for both health and the majority of biological functions. With the recognised importance of sleep, sleep habits of elite athletes are a popular topic. To date there has been limited research conducted specifically on sleep in athlete populations. Through a series of four studies, the current PhD aimed to enhance the understanding of sleep habits of elite level athletes. The specific purpose of the thesis was to explore sleep behaviour, complaints, and mechanisms within elite level athletes subjectively and objectively during periods of competition, to advance the understanding of the sleep habits in this population. Study One was a cross-sectional questionnaire to identify the occurrence and reported sleep complaints of 283 Olympic and professional athletes prior to important competitions. Study Two objectively and pragmatically monitored four netball state teams via actigraphy through a multi-day national tournament and related findings to final competition standings. Study Three, an observational study, explored the potential physiological, neuroendocrine, and psychometric mechanisms responsible for sleep complaints following a night game. Finally, Study Four examined the effectiveness of a neurofeedback intervention for improving sleep in athletes. Questionnaires from 283 individual and team sport athletes highlighted that poor sleep is common (64%) the night before critical competitions (Study One). Athletes reported problems falling asleep (82.1%) due to internal factors such as "thoughts about the competition" and "nervousness". It appeared that whilst sleep disturbances were confirmed by athletes prior to competition, the sleep complaints were predominantly situational and not associated with poor sleep in general. Sleep education therefore requires a situational focus (i.e. night games and competitions). The importance of sleep for athletic performance was demonstrated during a multi-day national netball tournament with increased sleep durations associated with a higher final tournament placing (r = -0.68) (Study Two). However, netballers experienced shorter sleep durations following evening games (7:08 ± 00:45 h) in comparison with afternoon games (7:37 ± 1:06 h). Finding from Study Three provided further support for poor athlete sleep following night games, with reduced sleep durations and efficiencies with early awakenings and poorer subjective sleep ratings reported in athletes after a night-game compared with a time-matched rest day. Athletes with a tendency towards a high trait arousal were more susceptible to sleep complaints following the night game. No differences were observed for core temperature and cortisol measures at bedtime following the night game compared to the time matched control day, despite these two physiological measures postulated to influence sleep. Based on findings from Studies One, Two and Three, a non-pharmacological sleep intervention of neurofeedback (feedback intervening on the level of the central nervous system using electroencephalography) was developed an examined for its effectiveness in optimising sleep in athletes. Neurofeedback was found to improve overall reported sleep problems measured through the Pittsburgh Sleep Quality Index, increase sleep efficiency, and reduce sleep onset latency in the home environment compared with a placebo group using actigraphy. However, no differences were observed for sleep measures between the neurofeedback and a sham treatment when measured by polysomnography. Despite improvements in subjective measures and sleep onset latency in the home environment further exploration is warranted before neurofeedback is universally adopted in athletes as a treatment modality. Due to learned regulation of specific cortical networks, neurofeedback may however be an alternate modality for specific problematic elite level athletes when traditional behavioural modifications (sleep hygiene) methods are not effective in enhancing poor sleep. In summary, the current series of studies provides a foundation for understanding sleep in athletes. The results demonstrate sleep disruption is indeed prevalent around competition and may impact competition standings. Despite common assumptions in literature around the mechanistic reasons responsible for night game sleep complaints, trait arousal was found to correlate to poor sleep following night games. In addition, neurofeedback emerged as a potential novel sleep intervention for targeted individuals however further exploration is warranted before it is considered a routine sleep strategy for elite level athletes. Overall, the studies provide useful information that can be used by coaches and staff to develop targeted sleep education to enhance the wellbeing and performance of elite level athletes.
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