To date, the known literature on the impact of sleep on exercise physical performance remains limited. Nevertheless, one important element that is highlighted in these studies is that everyone responds differently to insufficient sleep. For some, there may be little to no interference, while for others they find themselves at a great disadvantage when they don’t get their nightly sleep requirement. Overall, however, it can be said that the greater the sleep loss, the greater will be its effects on performance, particularly when the activity holds a strong cognitive component.
As outlined in Are you getting sufficient sleep? sleep loss can come in multiple forms and can accumulate over time to create sleep debt.
Furthermore, in addition to it direct impact on performance, it is also important to note that sleep plays a crucial role in cellular, muscle and tissue recovery, as well as in the development of muscle memory and learning. Insufficient sleep also impairs energy stores through its actions on glucose metabolism and insulin sensitivity. Moreover, prolonged periods of sleep loss will disrupt the autonomic nervous system, which puts the individual at risk of developing overtraining symptoms. As such, insufficient sleep through a variety of mechanisms also indirectly impair physical and athletic performance.
For the effects of sleep on our physical performance, studies have shown that sleep appears to have little to no impact on the body’s physiological and muscular response to exercise, including maximal output (one rep max), peak power, peak velocity and cadence, etc.
Therefore, periods of sleep loss may not have a strong impact for the standard gym session that focuses on weight lifting and/or cardio activities. However, although studies suggest that the physical component of a training, sport, or athletic performance may not or only be a little impacted by sleep loss, various studies report that the cognitive component becomes greatly impaired when sleep needs are not met.
As such, perceived effort, time to exhaustion and to a larger scale endurance all tend to be affected by sleep loss, and this more so when sleep loss is significant. This effect may be the result of lower levels of motivation and higher emotional response when sleep is compromised.
Sleep loss also increases variability in levels of alertness and reaction times, particularly in sustained activities. As a result, when a person is sleep deprived, there are instances of reduced alertness and slowed reaction intermixed with periods of ‘normal’ reaction times. The more a person is deprived of sleep, the more frequent these slowed reactions are observed. Physiological studies have shown that these instances of reduced alertness and slowed reaction are the result of micro-sleep episodes interjecting into wakefulness. Greater and unpredictable variability in attention and reactiveness can hinder performances where quick reaction is needed, including sports such as tennis, as well as any form of combat sport.
In league with reaction times, sleep loss also increases the variability in all cognitive responses including an increase in error rate. For sports with a strong cognitive element, such as hockey, football, and brazilian jiu jitsu, to name just a few, sleep loss can impact training outcome as well as competition and game performance.
What is interesting, however, is that training habits and familiarity are also factors on the influence of sleep on performance. As such, the more an individual is used to a form of physical training (ex. running) and the more the body is adapted to such a training, the less sleep loss will impact its performance. This may be due to the development of muscle memory, where the mental exercise and cognitive load associated to this training is reduced and the body more readily and naturally reacts accordingly.
In summary, sleep loss and accumulated sleep debt can impair our physical performance, particularly when there is a strong cognitive component associated to the activity. However, its impact is dependent on a variety of factors including individual variability, the type of training and sport as well as training familiarity and habit.
Prioritizing a good night’s sleep, and this on a daily basis, will help to reduce these effects on our everyday performance, as well as motivation towards training. For tips and tricks on how to optimize your nightly sleep, check out The Sleepyhead’s Sleep Hack section.
Selected Supporting References
- Fullagar, H. H., Skorski, S., Duffield, R., Hammes, D., Coutts, A. J., & Meyer, T. (2015). Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise. Sports Medicine, 45(2), 161-186.
- Doran, S. M., Van Dongen, H. P., & Dinges, D. F. (2001). Sustained attention performance during sleep deprivation: evidence of state instability. Archives Italiennes de Biologie, 139(3), 253-267.
- Van Den Berg, J., & Neely, G. (2006). Performance on a simple reaction time task while sleep deprived. Perceptual and Motor Skills, 102(2), 589-599.
- Knutson, K. L., Spiegel, K., Penev, P., & Van Cauter, E. (2007). The metabolic consequences of sleep deprivation. Sleep Medicine Reviews, 11(3), 163-178.