The benefits of getting a good night’s sleep are rarely debated. Most evidence suggests adults need 7-9 hours; however, the exact number varies based on the individual. Sleep allows for recovery, repair, and restoration of physiological and psychological functions. Can it also be critical to exercise performance and what you get out of your workouts? The answer is not so clear; let’s explore more.
Physiological Role of Sleep
As stated above, sleep acts as a period of recovery, during which hormones responsible for regeneration and repair of tissue (such as growth hormone) are released. This, coupled with the still state of the body, results in the perfect combination of factors to allow the body to restore itself from daily wear-and-tear. In addition to allowing for tissue recovery and repair, emerging research seems to suggest that sleep aids in draining waste product from the brain into the lymphatic system (the body’s garbage disposal). This, along with other neurophysiological changes, results in improved cognitive function and mood.
Sleep and Response to Exercise
The military has conducted much of the research on sleep deprivation to determine minimal sleep needs of soldiers; nevertheless, we can learn something from this research (albeit inconclusive).
Some research suggests that sleep deprivation results in a blunted fight-or-flight hormone response. This would result in lower exercise heart rate, lower core temperature, and decreased mobilization of fuels (fat and carbohydrate); all of this can impair exercise performance. This response has been observed in some, but by no means, all of the research. Most research still suggests that hyperventilation occurs more rapidly in individuals who are sleep deprived; this too would impair exercise performance. Finally, impaired growth hormone secretion, as a result of sleeplessness, can affect recovery and thereby exercise performance. However, not all research suggests this phenomenon occurs consistently.
What is of less debate, is that sleep deprivation does lead to higher rates of perceived exertion when exercising. Indeed, people perceive exercise to be harder when they are sleep deprived, and as a result, tend to terminate exercise sooner. This finding appears to be more consistent through out the research. Although the precise mechanism has not yet been identified, the results seem to be clear; well-rested individuals are in a better mental state to perform exercise.
If you are looking to get the most out of your workout program in terms of performance and body composition improvement, 7 hours seems to be a critical threshold. If nothing else, 7 hours of sleep per night ensures that perceived exertion and psychological tolerance for exercise remain high. This will help push you through higher intensity workouts. Also, try to keep sleep patterns consistent. Keeping your biorhythms consistent will aid in the release of growth hormone (at night) and testosterone (early morning), which aid in recovery and performance.