Assessment of sleep characteristics of elite team sport athletes

Despite the known restorative effects of sleep and the important role it may play in minimising fatigue and optimising adaptation from training, it has been suggested that athletes exhibit poorer sleep characteristics when compared to the general population. Whilst there have been investigations of the sleep characteristics exhibited during competition, analysis of the objective sleep characteristics of team sport athletes prior to and during important competition is limited, particularly in elite female athletes. In addition to the competition itself, there are a number of factors that may influence an athlete’s sleep. These include the training and competition schedule, phases of training and competition, internal and external training load, the athlete’s sleep environment, and domestic and international travel. However, the impact of a combination of these factors on objective sleep has rarely been explored in elite team sport athletes. Therefore, the main aim of this thesis was to investigate the objective sleep characteristics of elite male and female team sport athletes during competition. Three studies were conducted in a high performance sport environments to assess: (1) the impact of match start time and days relative to a match on sleep; (2) the relationships between sleep, training load and well-being; and (3) the impact of the quality and quantity of sleep obtained during a long-haul flight on competition sleep and perceptual measures including well-being and jetlag.

Study 1 assessed the objective sleep characteristics, via wrist worn actigraphy, of 45 elite male Australian Football (AF) players during the pre-season (habitual) and across four home matches during the competitive season. For each match start time, the 22 participants who were selected to play were assigned an activity monitor to be worn the night before (-1), night of (0), one night after (+1), and two nights after (+2) each match. Differences observed in sleep onset latency (ES=0.11 ± 0.16), sleep rating (ES=0.08 ± 0.14) and sleep duration (ES=0.08 ± 0.01) between competition and habitual periods were trivial. Sleep efficiency (%) was almost certainly higher during competition than habitual, however this was not reflected in the subjective rating of sleep quality. In many cases, the differences between match start times were trivial or unclear. The evening match start time, compared to all other start times, resulted in the clearest differences (e.g., evening matches had a likely longer sleep latency and almost certainly lower sleep efficiency). The differences in sleep characteristics based on days relative to the match were primarily trivial, however there were almost certain decreases in sleep duration for the night of the match compared to +1 and +2 nights post-match. The findings of this study indicated that, in general, elite AF competition does not appear to cause substantial disruption to sleep characteristics when compared to habitual sleep. Whilst the match start time had some impact on sleep variables, it appears that any match, regardless of match start time, may cause disruption to players’ sleep characteristics. The clearest disruption to AF players’ sleep occurred in the nights (+1 and +2) immediately following a match, which provides an ideal opportunity for intervention to optimise sleep and recovery. Importantly, the subjective ratings of sleep from shortened well-being questionnaires, used routinely in the high performance environment appear limited in their ability to accurately provide an indication of sleep quality.
It is recognised that numerous factors may influence the sleep characteristics of AF players, including player well-being and training and match day load. Nevertheless, the relationships between load, well-being and sleep prior to and following training and matches are not well understood.1 Study 2 assessed the association between objective sleep characteristics, self-reported measures of well-being and external load of 38 elite male AF players over a 15-day pre-season training period. External load was assessed during main field sessions and self-ratings of well-being were collected daily. Canonical correlations were moderate between pre training sleep and training load (r range = 0.32–0.49), pre training sleep and well-being (r = 0.32), and well-being and post training sleep (r = 0.36). Moderate-to-strong canonical correlations were observed between dimensions representing training load and post training sleep (r range = 0.31 to 0.67). Player Load TM (PL) and Player Load TM 2D (PL2D) showed the greatest association to pre and post training objective sleep characteristics and well-being. External load metrics PL and PL2D showed the greatest association between both objective sleep characteristics and well-being measures in AF players. This association was observed both prior to and following main AF training sessions. Fragmented sleep was associated with players completing the following training session with a higher PL2D, and increased wake bouts were associated with lower mood and higher soreness ratings. Our findings highlight that the relationship between objective sleep characteristics, training load and well-being are not defined by one measure (e.g., sleep duration). Instead, a complex interaction of sleep variables may influence both external load and the well-being of AF players. These findings have implications for practitioners, particularly when choosing variables to monitor AF players’ sleep to assist in the planning and evaluation of training.

The sleep characteristics for both Study 1 and 2 were assessed in players’ habitual sleep environments, however it is often a requirement for an elite team sport athlete to travel both domestically and internationally for competition.2-5 In order to investigate the impact of international travel on the sleep characteristics, well-being and performance of elite team sport athletes,6 the participant group for Study 3 was extended to elite female cricket players, as players are required to travel both domestically and internationally for competition. There have been no assessments of the objective in-flight sleep characteristics when athletes have the ability to lie flat whilst travelling in business class, however the difficulties of obtaining good quantity and quantity of sleep during long-haul travel are well documented,4,7 Study 3 assessed the impact of the quality and quantity of sleep during an international flight on subsequent objective sleep characteristics, training and match day load, self-reported well-being, and perceptions of jetlag in 11 elite female cricketers during an International Cricket Council T20 Women’s World Cup. To our knowledge, Study 3 is the first objective assessment of the in-flight sleep of elite team sport athletes seated in business class during an international flight. The results of Study 3 indicate that maximising the opportunity for in-flight sleep quality and quantity by planning the team departure time and business class seat selection appear to benefit elite female cricket players’ recovery and sleep exhibited during competition. The quality of sleep obtained in-flight had an impact on the self-reported measures of fatigue during the tournament. Players with a lower in-flight sleep efficiency reported higher levels of fatigue during the tournament. Study 2 highlighted that fragmented sleep prior to a main training session was associated with lower ratings of mood and increased ratings of soreness. This further supports that the quality and quantity of in-flight sleep may have had a positive impact on an athlete’s overall well-being and readiness to train upon arrival at the international competition destination. The preservation of both the sleep quality and quantity during long-haul travel may also be an important strategy to manage jetlag.3,8 Players that slept for longer during the flight presented with minimal perceptions of jetlag and this was maintained across the monitoring period. In contrast, players with lower in-flight sleep duration reported some perceptions of jetlag, which improved two days after arrival at the destination. It is acknowledged that the financial constraints of travelling business class may be a limitation for elite team sporting organisations, however the investment to achieve sleep quality and quantity similar to habitual values prior to an important international competition may outweigh the costs associated with the alternative approach of an arriving days earlier (e.g., accommodation) to facilitate recovery from travel.
In summary, the three studies in this thesis add to the knowledge of the objective sleep characteristics of elite male and female team sport athletes exhibited during competition. Our findings demonstrate that the sleep characteristics during competition are not compromised when compared to habitual. However, the habitual characteristics were not optimal, providing the greatest opportunity for intervention. The findings provide high performance practitioners and coaches with information to assist with the implementation of individualised and team strategies to optimise the sleep, well-being and performance of elite team sport athletes. Furthermore, preserving the sleep quality and quantity during international travel should be considered when planning travel and training upon arrival at the international competition destination.