Sleep and performance in elite level athletes

There is a widespread belief among elite level athletes and their coaches that adequate sleep is pre-requisite for those seeking to achieve optimum performance. Despite the prevalence of this belief, combined with the common occurance of sleep complaints among athletes, there has been surprisingly little empirical investigation of sleep in this population; the vast majority of sleep research takes place in normal populations, and employs methods of sleep disturbance that are not relevant to elite level athletes. When athletes have been studied, investigations thus far have failed to measure sleep objectively during the competitive season, and have relied on subjective and retrospective self-report. The aim of this thesis has been to examine the prevalence of sleep disturbance among elite level athletes, and to investigate the impact that sleep can have on subsequent performance both in training for competition and in competition itself. The impact that training and competing in elite level sport could have on sleep was also investigated, as were a number of other factors related to elite level competition. A total of 68 elite level athletes, both male and female, from 3 different sports (football, basketball, swimming), volunteered to have their sleep measured by wrist actigraphy for a period of at least 2 weeks. Twenty-seven age-matched sedentary participants were similarly recruited to act as a control group. Thirty-three professional football players, playing in either an England and Wales Premiership or Championship football club continued to have their sleep measured by wrist actigraphy for a period of eight weeks of the regular competitive season, during which their on-pitch performance was measured by means of the ProZone® player tracking system, and their performance in training was measured by the Catapult X3® GPS system. Both measures are widely used currently to measure performance in professional football, ensuring that performance was measured as it occurred naturally instead of in a contrived setting. Wrist actigraphy was similarly chosen since it allows for long term objective measurement of sleep. In agreement with anecdotal reports and previous research, evidence of a significant level of sleep disturbance was found among all the types of elite athletes studied. A number of stressors associated with elite competition also demonstrated a significant impact on sleep, particularly to sleep timing following matches, and more generally as a consequence of physical activity during evening matches. Sleep did not have a statistically significant impact on subsequent performance during matches, although, given the narrow margins between success and failure involved in competing at such a high level, the size of the effect in evidence may still have important implications for athletes and coaches. Sleep also demonstrated a significant impact on performance during training. The evidence of significant sleep disturbance has serious implications for elite level athletes; on its own the level of sleep disturbance has a number of potentially adverse consequences, such as increased risk of infection and illness, compromised metabolism, and sub-optimal recovery from training, potentially serious factors for those training for optimal performance. In addition, the consequences that poor sleep has on training could hamper efforts to prepare properly for elite athletic competition, as well as having a marginal impact on performance itself.