Sleep is essential for survival. Its quality is one of the key factors in restoring the body and therefore directly affects our activities and in our case, sports performance.
All beings with central nervous system present what we understand as “sleep”. Sleep is a normal condition characterized by a reduction in perception and limited interaction with the environment, during which the body is under-functioning in terms of its externally observed effect. Science has distinguished 2 stages – types of sleep. The classification is based on the differences in the EEG that records the brain functions.
The stages of sleep are NREM (Non-Rapid Eye Movement, stages 1, 2, 3 and 4) and REM (Rapid Eye Movement, Stage 5). The five overall stages last about 90 minutes and are cycled three to six times during the night. During REM sleep we see our dreams.
During sleep, our body regains its strength to be able to function properly. Hormones are secreted (including growth hormone, in stage 3) to restore the body from daily stress and intense physical activity including exercise. Restoration is universal and includes the reconstruction of damaged tissues (such as the muscular system) as well as the strengthening of the immune system but also improving brain functions such as memory or ability and speed of response to external stimuli.
Transitions between waking and sleeping are controlled and regulated by the brain, which also plays a key role in terms of duration and quality – depth – of sleep.
However, it is very important to bear in mind that sleep is also strongly influenced by external factors such as light, air travel and taking substances characterized by their stimulation action οn our nervous system, such as caffeine, nicotine, alcohol and medicines such as amphetamines, ephedrine etc. Physical conditions such as anxiety, high pressure, physical pain and intense noise can also have a negative impact on sleep duration and quality.
Referring to light it is important to look deeper into the negative effect of blue light. Blue light and its effect on sleep have been studied thoroughly by science. One of Harvard’s most important studies has shown that blue light emitted by mobile phones, tablets and TV, especially when exposed near nighttime sleep, greatly affects the secretion of melatonin hormone, which regulates the onset of sleep. Blue light makes it difficult for us to sleep, which results to shorter sleep duration and poor quality. This is bad for hormonal secretion, such as less growth hormone, resulting in poor recovery. But it also influences the circadian rhythm of sleep, our biological clock, when our body is asleep and awake. The negative effects of blue light are minimal to zero when we do not expose it to at least 2 hours before bedtime.
The power of sleep is immeasurable and science still explores the benefits and the effects of lack of sleep and the evolution of brain function and plasticity over time and the role that ultimately plays in our lives.