Sleep of athletes – problems and possible solutions

Human performances are highly dependent on one of the main biological rhythms, namely the sleep–wake rhythm. This rhythm is driven by the living clock and is functional in the adaptation to day–night differences in the environment. The athlete, like all humans, is set up to be awake and in good shape to exercise during the day, and to sleep and recover during the night. Regular vigorous physical activity, such as the light–dark cycle or social cues, can be considered as a zeitgeber. It has been shown to reinforce the synchronisation of human circadian rhythms, which means that physically active people have a stronger circadian rhythmicity than those who are sedentary. Sleep and exercise also have strong relationships that are independent of the biological clock. On the one hand, athletic performances have been shown to be dependent upon both the quality and the quantity of sleep that has been taken before the competition. The detrimental effects of sleep deprivation are shown by increased lapsing, cognitive slowing, memory impairment, decreased vigilance and sustained attention, and shift in optimum response capability. Its effects on physical performance are manifested as a decline in the ability to perform maximal exercise. Aerobic and anaerobic pathways are both affected, as are fatigue and recovery processes. Sleep deprivation can also phase shift and decrease the amplitude of many individual rhythms. All these effects are dependent on the timing and the length of the waking state, but many of them are seen after only few hours of sleep deprivation. On the other hand, exercise by itself has been shown to have an impact on subsequent sleep. Sleep latencies and fragmentation are reduced and the deep slow wave sleep is increased. It is beyond doubt that athletes need more sleep than sedentary people, and so athletes, in order to perform optimally, need to respect the “rules” imposed by the circadian pacemaker for establishing consistent sleep periods.