Before looking at the advantages of sport on sleep and vice versa, you need to understand its different phases. In reality it is composed of two very distinct phases which form a 90 minute cycle that repeats 5 or 6 times a night. These two phases are the NREM and the REM sleep phases.
The NREM phase has 4 parts: falling asleep and three deeper sleep periods. The last two are known as slow-wave sleep (SWS).
The REM phase of sleep is when we dream and represents around 25% of the total amount of time we spend asleep. It's a lighter period of sleep that stretches out longer and longer throughout the night. The muscles are completely relaxed but the brain is just as active as during the day.
It is also interesting to note that, according to some studies, certain periods, between 11pm and 7 am and around 1pm, are more favourable to falling asleep. On the contrary, the periods from 10am to 11.30 and 5pm to 8 are better for doing physical and intellectual activities. What's more, our bed time affects the quality and quantity of our sleep, with the average person needing 8 hours of sleep per night.
2. The Benefits Of Sport For Sleep And The Benefits Of Sleep For Athletes
According to several studies, sport makes us sleep more deeply but its effects on NREM sleep are only valid if the athlete uses more than 60% of their breathing capacity during their activity.
Besides this, intensive sport prolongs the amount of time we sleep for and changes its quality: athletes fall asleep faster and their NREM sleep lasts longer, whereas their REM sleep is shortened.
The positive effects of physical activity on sleep are expressed in several ways. During SWS, the cellular growth hormones, which allow us to rebuild our muscle tissues, are activated in large numbers. Additionally, the level of hormones produced is higher than during a training session, whatever its intensity.
SWS also leads to a drop in the excitability of brain cells and, as these control the muscles, it causes them to relax. This relaxation particularly benefits the muscles that maintain your posture and those used the night before. The muscle cells can therefore regenerate and rebuild their energy stores.
Sport also allows the body to reach a lower temperature during sleep, which aids protein biosynthesis. What's more, the inactivity we are plunged into allows us to remove the toxins and waste that have built up in the body more quickly, which is essential for athletes.
3. Precautions To Take For An Effective Sleep
But to achieve an optimal relationship between the athlete and sleep, a few precautions are required:
-Deep NREM sleep depends on the fatigue from which you need to recover. Consequently, the longer you were awake the day before, the longer you need to sleep. If you sleep less than you need, the amount of REM sleep drops. If the length of your sleep is very short, your health is endangered. A lack of sleep leads to a risk of drowsiness which reduces your reflexes, slows down movements and makes your limbs feel heavy. However, too much sleep isn't good either as it causes the same types of disadvantage. It can be very frustrating for athletes if it means they can't train as they would like.
-You should avoid training late in the evening as this delays the onset of sleep by increasing your body temperature. Your internal clock becomes upset and the quality of sleep falls. In fact, sleep at the start of the night tends to be composed of SWS whereas in the morning there tends to be more REM. However, SWS is better for recovery!
-You should be aware of your diet and adapt it to suit your sports-related needs. To do so, a nutritional balance is required. For example, consuming too many proteins reduces the total amount of sleep but increases the duration of REM sleep. On the other hand, consuming meals rich in slow and fast carbohydrates increases the total duration of sleep and favours SWS.
-Finally, overtraining should be avoided as it often causes sleep problems…