It is anecdotally known that sleep is at the top of your priorities when trying to optimize recovery. Frank (2006) highlighted a variety of effects of sleep on the human body both psychological and physiological. He found a relationship between duration and timing of sleep and the immune system. To strengthen this point, Hausswirth and Mujika (2013), showed that a direct consequence of lack of sleep is an increase in pro inflammatory factors, which can promote immune system dysfunction. He also proved that sleeping has an effect on the nervous system for both restoration and detoxification on top of cognitive functions such as: learning, memory and neurotransmission.
In regards to sports, swimmers that slept only 2.5 hours for fours nights, showed a significant change in mood state, increased depression, tension, confusion, fatigue and anger, however no change was seen in lung function or swimming performance. It has also been shown that sleep might have a more detrimental effect on long lasting activities/sports compared to short single effort activities (Reilly and Edwards, 2007).
Recovery strategies such as hydrotherapy can influence skin temperature, which positively influences sleep quality. Recent studies show that cold-water immersion can potentially improve sleep quality therefore improving recovery and subsequent performance. Whereas several nights of sleep deprivation, corresponds to an increase in pain perception, decreased sociability, increase in “body discomfort” and pain, which were all reversed after sleeping habits returned to their normal status. So what can we learn from this? That it is important to have a good nights sleep and there is a considerably greater risk (1.7 times more) of injury in people who have less than 8 hours sleep every night.