Sleep in female athletes : exploring the risk factors for disturbance and implications for recovery

  • Kathleen Miles

Student thesis: Doctoral Thesis

Abstract

Sleep is an integral component in the preparation for, and recovery from, athletic training and
competition. However, the majority of evidence is in male athlete populations, and
there remains limited published data on the sleep of female athletes. Therefore, the aim of this
thesis was to systematically review the current research on female athlete sleep, and then to add
to it through targeted observational studies, as well a randomised controlled trial investigating
the efficacy of α-lactalbumin supplementation to improve sleep.
Chapter One and Chapter Two provide an overview of the thesis, and a narrative review
summarising the background theory of sleep, and possible interventions to improve athlete sleep.
These chapters provide context and background for the subsequent studies included in the thesis.
Chapter Three was a systematic review with meta-analysis, that aimed to examine the patterns,
duration and quality of sleep among elite female athletes, and consider the impact of situational
challenges and their effects on the sleep of elite female athletes. A total of 38 studies were
included, and a meta-analysis was performed on 15 studies that assessed sleep during habitual
periods using actigraphy. Evidence suggests female athletes are achieving satisfactory
objective sleep quantity (total sleep time [TST], 7.8 h) and quality (sleep efficiency
[SE], 86.7%) during habitual periods, however most of the current habitual sleep evidence is with
netball (n = 98 out of 238) and soccer (n = 53 out of 238) athletes. In addition, female athletes
experience sleep disturbances pre- and post-situational challenges. The review also identified high
variability of objective sleep outcomes, demonstrating the individual nature of habitual female
athlete sleep. Overall, Chapter Three highlighted that future research must focus on optimising the
sleep appraisal methods and creating high-quality study designs in a broader
number of sports.
Chapter Four compared the habitual sleep of female basketball and soccer athletes to age and sex
matched controls and characterised the sleep of basketball and soccer athletes at different
competition locations and on the days surrounding competition. Chapter Four found during habitual
conditions, basketball athletes slept longer (7.4 ± 1.5 h) than soccer athletes (7.0 ± 1.2 h, p <
0.001) and controls (7.3 ± 1.2 h, p = 0.002). During competition, basketballers went to bed earlier
(23:49 ± 01:25) and woke earlier (07:22 ± 01:59) following Away games compared to soccer athletes
(00:10 ± 01:45 and 08:13 ± 01:45). The findings from Chapter Four highlight that sleep
recommendations and interventions need to be individualised to specific sports, athlete
groups and competition scenarios encountered during a season.
Chapter Five assessed the sleep hygiene knowledge of high performance team sport coaches and sports
science support staff, the sleep practices these individuals implement with athletes, and the
barriers to the more frequent use of these practices. A sample of 86 Australian coaches and sports
science support staff working within high performance team sport were recruited to complete a
four-part questionnaire. Chapter Five identified that team sport coaches and sports science support
staff have adequate overall sleep hygiene knowledge (15.3 ± 2.9, score range 0-20), yet some
specific areas (e.g. sleep-wake cycle behaviours) warrant improvement. There were limited sleep
practices implemented with athletes, particularly regarding the promotion of sleep hygiene (43% had
promoted sleep hygiene). A novel finding of Chapter Five was that there was an increased resistance
to the implementation of sleep hygiene strategies by coaches and support staff who work with female
athletes. Overall, educational sleep resources need to
be developed for coaches and support staff to improve knowledge and athlete intervention.
Lastly, Chapter Six determined the efficacy of α-lactalbumin supplementation for improving sleep
and performance recovery following simulated evening competition in female athletes. Sixteen
trained females participated in this randomised double-blind three-arm crossover study,
whereby sleep was monitored using polysomnography. The results of Chapter Six indicate
that α-lactalbumin supplementation may be useful for retaining some sleep
characteristics following evening competition, for example, non-rapid eye movement stage 2 sleep
increased by 2.7% post-competition in α-lactalbumin (A-LAC) but decreased in control (CON) (-3.8%)
and placebo (PLA) (-0.4%, p < 0.05). In addition, Yo-Yo Intermittent Recovery Test Level 1 distance
improved over time in A-LAC compared to CON and PLA (p < 0.05). Based upon these findings,
α-lactalbumin supplementation could be used by athletes to improve sleep and performance
recovery following evening training or competition. Further research on the efficacy of
α-lactalbumin supplementation during situations that are known to impair athlete sleep, such as
travel and demanding competition schedules, should be conducted.
Collectively, the findings from this body of research highlight the suboptimal objective and
subjective sleep female athletes can experience during habitual conditions, as well as pre- and
post- situational challenges such as training and competition. Implementing a whey protein α-
lactalbumin supplement following a situational challenge to sleep such as evening
competition may help female athletes with their sleep and next-day performance recovery.


Date of Award2021
Original languageEnglish
SupervisorKate Pumpa (Supervisor) & Brad Clark (Supervisor)

Cite this

'