Professor E.A. Korabelnikova
PhD, head of the Department of neurology D. Degterev
PhD, associate Professor E. Bezuglov
I.M. Sechenov 1-st Moscow state medical University (Sechenov University), Moscow
head doctor of the Russian national football team, vice-president of the all-Russian athletics Federation Moscow state medical Center named after A. S. Loginov, Moscow, Russia
Sechenov1-st Moscow state medical University (Sechenov University), Moscow

Keywords: professional athletes, sleep disorders, pharmacotherapy, melatonin, non-medical methods of correction.

Introduction. Modern science convincingly proves that sleep is not a rest, but an active, complex, multifunctional process that performs many vital functions and is one of the most important aspects of human life. It contributes to the strengthening and preservation of health, psychophysical condition and performance. Representatives of certain types of professional activities in connection with high energy costs need more than a person needs on average, the amount of sleep. This type of activity includes professional sports. Modern sports are characterized by large loads that place high demands on the body of athletes. In order to increase the productivity of your workout, you need to choose the best recovery methods. Among them an important place is occupied by healthy sleep [9, 10, 12, 23, 24, 28], restoring energy costs and contributing to high sports results [11, 16].

Objective of the article is to analyze the literature devoted to the study of the role of sleep for athletes, scientific information about the representation, nature and consequences of its violations, to summarize and structure data related to the strategy for optimizing sleep in this population group. The analysis of literature data was carried out using the following methods: descriptive (descriptive), systematization, visualization (representation in the form of diagrams, tables).

The importance of healthy sleep for achieving good sports results is confirmed by the results of a number of scientific studies. So, in a survey of almost 900 professional athletes, sleep was named by the vast majority as the most important means of recovery, regardless of gender, sport and success [29].

Sleep disturbance reduces the level of testosterone and insulin-like growth factor 1, and therefore glycogen synthesis, which prevents muscle recovery after damage [7]. Improved sleep allows athletes to demonstrate a greater speed of starting reaction, less sprint time, greater accuracy and speed of movement. A study of the Stanford University men's basketball team on the background of an increase in the sleep duration to 10 hours showed a faster sprint and greater shooting accuracy. The free throw percentage increased by 9%, and the 3-point field goal percentage increased by 9.2% [17].

The influence of sleep disorders on cognitive functions, such as concentration, memory, and learning ability, has been proven. Sleep loss impairs the functional state of the frontal lobes of the brain and, as a result, has a negative impact on programming and decision-making [6].

As a result of the above-mentioned consequences of sleep disorders, one can see an increase in injuries [21, 26]. For example, teenagers who sleep less than 8 hours a day are more likely (1.7 times) to suffer significant injuries than those who sleep more than 8 hours a day. Data presented at the American Academy of Pediatrics (AAP) National Conference shows that young athletes who sleep for at least 8 hours a day are 68% less likely, and according to other researchers, 1.7 times less likely to get injured than others. The authors consider the amount of sleep as the strongest predictor of injuries [21]. Sleep disorders negatively affect the overall physical and mental well-being of athletes, worsen the immune status, and lead to the formation of "cumulative fatigue" [14].

Thus, sleep becomes a crucial factor for success for professional athletes. Sleep disorders eventually lead to a decrease in athletic performance and a shortened athletic career (see figure 2).

Figure 2. Mechanisms of influence of sleep disorders on sports results.

Prerequisites and variants of sleep disorders in professional athletes. Despite the observance of a sports regime and adherence to a healthy lifestyle, sleep disorders are also found in athletes. The following main factors may contribute to sleep disorders [5, 9, 10, 13, 22, 25, 28]: production of adrenaline, which leads to hyperactivation and disrupts the process of falling asleep; increased body temperature; release of energy intended for physical activity during training; fatigue caused by too much work; excessive muscle tension after a workout that was not completed by stretching; unused energy when the load is reduced for some reason after a long period of intensive training; exercise less than 4 hours before bedtime; late dinner; frequent foreign travel and sleep in various conditions; emotional stress; use of stimulants; excessive hydration or dehydration before bedtime.

Paradoxically, many athletes sleep less during intense exercise, when they need sleep most. The total sleep time for elite athletes can often fall below the minimum 7 hours recommended for optimal health, especially during periods of high physical activity [18]. In the survey, 42% of college athletes reported poor sleep, as evidenced by a score of more than 5 points on the Pittsburgh sleep quality Index (PSQI). In Addition, 38% of athletes slept less than 7 hours a day, and more than 50% had symptoms of excessive daytime sleepiness, as measured by the Epworth sleepiness scale [18]. It is shown that every fourth athlete suffers from respiratory disorders during sleep, and every sixth uses sleeping pills during the playing season [3]. A survey of 256 students athletes (sambo, weightlifting, basketball, track and field, skiing and strength training), showed that only 54% of them have incomplete sleep, i.e. for various reasons they have not always explicable awakenings. Due to sleep disorders, 37% of the subjects had reduced performance in training and sports activities, and 21% of the respondents could miss training sessions or lectures because they wanted to sleep. Some of them had respiratory disorders during sleep, leading to hypoxia, which disrupts the work of the entire body and reduces physical performance [1].

Currently, in professional sports, there is a tendency to increase the number of competitions in different geographical locations, which requires from athletes to make frequent long transmeridional flights. A sharp change in standard time is accompanied by a number of physiological reactions of the body, in particular, violation of circadian rhythms, which adversely affects the functional fitness and physical performance of athletes [2].

Psychological conditioning of the quality of night sleep of athletes has been confirmed by a number of studies [1, 4, 28]. Cases of insomnia on the eve of competitions and the associated state of overtraining are described [4]. Sleep may be disturbed in athletes with anxiety-depressive disorders [25].

A sleep optimization strategy for athletes. Sleep disorders in athletes can be easily corrected if a number of rules and recommendations are followed [26]. The main principles and approaches of non-drug correction of sleep disorders are shown in table 1.

Table 1. The main ways of non-drug optimization of sleep in professional athletes

Pharmacological correction of sleep disorders in the population of healthy athletes is used less often in order to avoid side effects in the form of a violation of morning well-being, influence on the motor and cognitive sphere in subsequent wakefulness. Practitioners of sports medicine use various classes of sleeping medications: GABA agonists, melatonin receptor agonists, antihistamines, and benzodiazepine derivatives (less frequently) [27]. Pharmacological effects on athletes' sleep are used to reduce overexcitation after training, to correct the sleep-wake cycle during transcontinental flights, and to treat insomnia.

Among the pharmacological drugs used to correct sleep disorders in athletes, the most popular are those that solve all of the above tasks and at the same time are as safe as possible and do not affect subsequent wakefulness. These drugs include melatonin-containing drugs, which is figuratively called "the hormone of the night", "Dracula-hormone". As a hormone of the pineal gland, it is involved in maintaining a normal circadian rhythm in humans. Drugs-synthetic analogues of melatonin allow us to normalize the level of this hormone in the central nervous system. They are quite effective and safe sleeping pills that can be recommended in all cases of sleep disorders in athletes of any age without any visible negative consequences and with a high degree of tolerance [23].

An important effect of melatonin is the maintenance of circadian rhythms, which is especially important for athletes who make frequent transcontinental flights. It is shown that the introduction of exogenous melatonin in the afternoon and evening hours of the daily cycle contributes to the phase shift to an earlier time in the circadian rhythm, which contributes to the sleep onset [4]. When taken in the early morning, exogenous melatonin contributes to the "delay" of the current circadian phase in the daily rhythm. This stimulation of phase shift and inducing sleep by administering melatonin during the daytime and evening hours can be used to alleviate the symptoms of desynchronosis (jet lag syndrome). Linking the time of melatonin administration to the new time zone can help overcome the symptoms of desynchronosis [2]. There is evidence that exogenous melatonin improves the condition of skeletal muscles [8], accelerates regeneration when they are damaged [20], increases their metabolism, strength and tone [19], and also affects physical endurance by preserving muscle and liver glycogen [15] and, as a result, sports results.

Conclusions

1. Sleep of professional athletes directly affects sports results.

2. The sleep of athletes is influenced by a number of factors, both external (external circumstances and sports environment) and internal (personality characteristics, health conditions, sleep-wake cycle).

3. Sleep disorders of athletes lead to deterioration of physical, cognitive, and mental indicators, which in turn impairs their professional performance.

4. Taking measures of medical and non-medical effects that can improve the sleep of athletes is recognized as the most important tool for improving their performance and recovery.

Summary. Thus, a healthy sleep is the key to the success of successful professional athletes. Despite the commitment to a healthy lifestyle, professional athletes are often found to be impaired, which is associated with a number of external as well as internal (individual) factors. Sleep disorders in athletes are fraught with a number of negative consequences, including deterioration of health and an increase in the frequency of injuries, which indicates the need to take a set of measures aimed at improving the quality of sleep.

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Corresponding author: fizkult@teoriya.ru

Abstract

 Professional athletes are more organized and committed to a healthy lifestyle, which in turn contributes to the observance of work and rest, including sleep hygiene.

Objective of the study was to analyze the literature devoted to the study of the role of sleep for athletes, scientific information about the representation, nature and consequences of its violations, to summarize and structure data related to the strategy for optimizing sleep in this population group. The analysis of literature data was carried out using the following methods: descriptive (descriptive), systematization, visualization (representation in the form of diagrams, tables).

The results of a number of studies show that sleep is extremely important for restoring the brain's energy expenditure, as well as for the normal functioning of memory and attention, which contributes to achieving high sports results. In this regard, sleep disorders in athletes are fraught with a number of negative consequences, including deterioration of health and an increase in the frequency of injuries, which indicates the need to take a set of measures aimed at improving the quality of sleep. The article presents data demonstrating the prerequisites, main manifestations, methods of drug and non-drug correction of sleep disorders in professional athletes.