The role of sleep in sport: the recovery effort and learning-memory - cognitive-decision-phase.

Cecilia Scassa MD

Ex Teacher Master Pro-Uefa  Coach-Technical Area Coverciano -FIGC.

In the previous article, we introduced the role of sleep in the general population, underlining its role as physical, cognitive, learning, memory and real disposal phase of neurotoxins accumulated in the brain during wakefulness.

In particular, science has widely documented the role of brain neurotoxin disposal in deep sleep phase 4, the role of memory consolidation and the fine difference in the concept of short-term and long-term learning that is defined respectively in phase 4 of the deep sleep and in the subsequent REM phase.

Various studies are highlighting more and more , as well as the general population, the importance of sleep on neurophysiology, cognitive function and mood of the athlete .

The sleep, as identified through studies on its de deprivation in terms of extension , has a role crucial in the athlete's performance, both for the phase of the recovery effort, or a more rapid recovery of an injury, both on the metabolism, on the cognitive- attentional role , on the consolidation of memory, that is, on the long-term fixation of a game pattern, taking the example of football, learned during training. Finally, the role on the athlete's mood and receptivity cannot be excluded.

In particular , it has been shown that for a consolidation in the memory and a precise metabolization of a game scheme never tried before the athlete is necessary to sleep , because it is precisely in phase 4 deep sleep and in the immediate subsequent phase REM ( Rapid Eyes Movements ) that neurotransmitters and metabolites essential for short and long term memory and for the recovery of the fatigue of the previous training are released.

Paradoxically, elite athletes have worse quality and quantity of sleep than the general population. This is probably the result of training times, competition stress / anxiety, muscle soreness, caffeine use and travel.

From this point of view, analyzing the literature, some considerations must be made. 

In fact, although it has been shown that there is a positive relationship between sleep and optimal performance, athletes often have a poor quality and quantity of sleep, with repercussions that are not always immediately recognizable.

In particular, the literature underlines the importance of not underestimating even mild apnea disorders during sleep and insomnia itself. On the contrary, app it is the management of a concussion more difficult for which it is recommended that a desired sleep deprivation in the first 24 h to reduce the risk of cerebral hematoma. 

After this critical period of time, patients and athletes with sleep deprivation may undergo an extension or aggravation of the results of concussion.

Sleep deprivation in athletes can affect their cognitive-physical performance (speed, endurance, neuro-cognitive functions, such as attention and memory, physical health (less risk of accidents, control of body weight).

Furthermore, the performance capacity in athletes depends on and the ability to recover or compared to the previous exercise.

The results indicate that the natural variation in the amount of sleep affects psychomotor vigilance to a greater extent than athletic performance. 

It has been documented that a night of compromised sleep may not be immediately problematic, but more extreme sleep loss or accumulated sleep debt can have more serious consequences.

These deficits have largely been attributed to the failures of alert attention , which many theorists believe forms the basis of the other more complex components of cognition .

In summary , the sleep deprivation seriously compromises the ability of human beings to respond to stimuli in a timely manner (vigilance and attention) and is at the base of the more complex components of cognitive decision-making, which are playing an increasingly important role in the modern sport involving high rhythms and, consequently, the ability and intelligence of the athlete to react as quickly as possible with the more effective motor response to more and different situations in the field.

First, sleep deprivation translates into a general slowdown in responses; secondly, the propensity of individuals to lose attention skills for long periods (> 500 ms ) increases, as well as making cognitive- decision- making errors , that is, of technique and execution of the established game tactics.

The studies reported in the literature, basically, shows n or that the phase of short storage but, according to others, also  long-term only if is supported by constant training, namely  the learning performed in training, it consolidates in step 4 of deep sleep and in the subsequent REM phase .

Further evidence comes from studies focused on the role of stage 4 and REM in athletes who have demonstrated how the deprivation of sleep REM not have had effects harmful on the execution of a task already previously learned.                 

In summary, as already anticipated in the previous article, sleep and especially REM sleep would have a decisive role in the maturation of the central nervous system , in fact during the REM phase there is an increase in brain activity . 

In experimental studies, men undergoing intensive learning sessions had a significant increase in REM sleep, further expression of the process of fixing data learned in long-term memory .  

These results confirm you the role of memory consolidation in REM and the role in the long-term memory, while in the learning phase and consolidation of a task or scheme nu or goes acquisition would be fundamental to the phase of deep sleep or stage 4. 

A very recent study examines the effects of sleep by EEG in young footballers of average age 16 years subjected to intense physical exercise compared to a control group with low intensity exercise.

Analyzes Sleep - EEG revealed that, compared with controls, players undergo high physical impact have shown greater the efficiency of sleep a latency of onset sleep reduced , less awakenings after the ' onset of sleep , the stage 4 and less sleep REM , with better daily performance . Also this study appears on  line with the importance of deep sleep in the learning phase of a scheme or new task and role, not least, the REM phase in the consolidation and recall the memory of a task already acquired .                      

It is therefore important to educate athletes on adequate duration, quality, and timing of sleep, as an additional parameter to improve short and long term performance and memory.