Among the many benefits of sleeping well, for athletes there is one very important reason and that’s why they need to sleep more hours: they need to restore the balance to their immune system. When taking part in sports, a series of processes take place in the body, triggering a response aimed at returning the body to its regular homeostatic balance, which is lost through the stress of doing exercise. In other words, it repairs the body from both the effort and the metabolic change it has undergone.
The first consequence of high-intensity training and heavy loads is muscle fibre stress and tearing. Repairing the immune system prompts an inflammatory response, the same response that is active during an infectious illness. In this case, the response repairs muscles, which will be strengthened when the process is complete. However, this response only takes place when we sleep and staying awake for long periods of time has the opposite effect. While awake, our body activates the anti-inflammatory response, partly to devote all of its energy and attention to the environment.
Thus, when an athlete does not get enough sleep, they partially “shut off” their immune system switch, delaying their full recovery.
Another imbalance created through sports practice is an increase in white blood cells. The main defence system cells not only increase in number; they also move to the external tissues, particularly the skin, in anticipation of a wound or injury. Thus, the repairing agents are prepared to act quickly. During post-exercise rest, the body returns to its regular state. The lymphocytes decrease while the number of other defence cells, the neutrophils, increase. This balance is maintained as long as we do not alter our sleep routines. Interestingly, this entire process is similar to what happens when we are fighting a cold or flu. These are the times when we tend to stay in bed and get more sleep.
During an illness, we feel more fatigued, this occurs to trigger the inflammatory response that we’ve mentioned. This is why athletes must also commit to regular rest as a necessary practice, with a minimum of eight hours of sleep at the same time each day. Changing the pattern for just one day will drastically change the athlete’s recovery pace from an immune system perspective.
Cytokines are one of the regulators of the entire balance of this system. They are secreted by certain types of cells and serve as a signal to activate and control inflammatory responses. The concentration of circulating cytokines reduces dramatically from just one night of poor sleep. Their job is to warn if there is a problem in a certain part of the body and to stimulate the activation of repair cells. Reducing the number of cytokines by sleeping less leads to an increase in recovery time for muscles, decrease personal performance, and increase the risk of suffering an injury or an illness.
Additionally, injuries are not just related to muscle recovery. The immune system also utilises sleep to reinforce its memory. It has been proven that those who sleep after getting a vaccine generate the antibodies that will protect them against the illness for life more quickly and in higher numbers. Likewise, our body learns to return to a homeostatic balance – the initial state for optimal performance in sports – more flexibly and efficiently when we sleep.
A lack of sleep or irregularity in the sleeping schedule is also a self-perpetuating process. Every time we sleep poorly, we are stimulating a series of metabolic processes aimed at keeping us awake. Thus, it is essential, especially for athletes, to learn a series of habits for improving sleep. This is very important for adolescents worldwide, who are affected by irregular sleep due to social jet-lag and the improper use of technology. Therefore, FC Barcelona and the AdSalutem Institute, in collaboration with Allianz, have been working together to create a Sleep Guide geared towards young athletes who train at La Masia. This guide contains explanations regarding the benefits of sleep and a complete series of recommendations for sports training with a clear message: the athlete who does not sleep well is limiting their chances of being the best.
The Barça Innovation Hub team