Sleep training for elite athletes
Elite athletes like Cristiano Ronaldo or German yachtsman Boris Herrmann sleep not only at night, but also several times a day. The reasons vary, and the benefits are questionable.
Good, restful sleep is of enormous importance for top athletes and can enable a performance increase of up to 3%. That can be the difference between victory and defeat in certain sports. During sleep, muscles regenerate and grow, movement sequences are internalized, and mental strength is gained. On the other hand, a lack of sleep influences the ability to concentrate, mood, reaction time and performance and can lead to physical illness.
However, for someone who sails around the world alone for months on end, it's impossible to get hours of sleep. Solo circumnavigator Boris Herrmann, therefore, trained himself to sleep only briefly, several times a day. But the nap in the final phase of the Vendée Globe 2021 proved to be his undoing. While he was sleeping, technical monitoring devices failed to sound the alarm and his boat collided with a fishing trawler. Herrmann subsequently failed to finish on the podium.
Other athletes also adjust their sleep to their specific needs. Boxers, for example, adjust their sleep rhythm so that they can perform particularly well during a bout scheduled for late at night, contrary to their natural internal clock.
Professional footballers such as Cristiano Ronaldo or Robert Lewandowski work with sleep therapists and nap several times a day according to sophisticated sleeping plans in the hope that this will help their bodies to regenerate more quickly.
Polyphasic sleep model particularly popular
Sleep researchers distinguish between three different sleep models: monophasic, biphasic and polyphasic. Most people sleep an average of seven hours at a time at night and thus have only one sleep phase (monophasic). Some still add a nap (biphasic). A pattern of three to six sleep phases per day of about 90 minutes each is called a polyphasic sleep model. This is typical for babies, but it's also adopted by some competitive athletes.
It usually takes two to three weeks to adapt to this new sleep pattern, Christian Zepp of the Psychological Institute at the German Sport University in Cologne told DW.
"You have to practice it, it's hard work. But a professional athlete will do everything in their power to improve performance... If you train yourself to do this, your body also learns to get into the important sleep phase more quickly and to break down its metabolic products more quickly."
Keeping to a sleep schedule is important
Athletes complain particularly often about sleep disorders caused by psychological pressure, stress before competitions, too intensive training or strenuous travel. However, interval sleep patterns are not necessary to improve performance. Athletes would actually sleep significantly better if they stuck to their sleep schedules and sleep hygiene, Zepp explained. This includes keeping to a regular time to go to bed, keeping the bedroom cool, having a light dinner and avoiding distractions such as smartphones.
But not everyone is disciplined enough to follow such rules — and the COVID-19 pandemic hasn't helped either. According to Zepp, it led some athletes to start going to bed later than usual.
"In 2020, I had a lot of athletes — especially young athletes — stop sticking to anything. They then went to bed at three in the morning and at some point wondered why they were no longer performing as well."
Differing assessments of power naps
Healthy sleep is cyclical; every 60 to 90 minutes the body goes through a sequence of light, normal and deep sleep phases, each cycle concluding with REM sleep (rapid eye movement/dream sleep), at the end of which you usually wake up. So you're not in deep sleep for the entire night — deep sleep accounts for only about 25% of total sleep time.
"While longer deep sleep phases can still be seen in the first half of the night, these decrease significantly in the second half," explained Cologne-based sleep researcher and psychologist Christine Hamm.
"Sleep is more easily disturbed, and waking phases become more frequent. It's known from basic research that you normally wake up as many as 25 times a night," Hamm added.
Good sleepers usually don't notice this because they quickly fall back asleep. On the other hand, poor sleepers often lie awake longer during nightly waking phases and can remember them well.
"Those who tend to have problems falling asleep and sleeping through the night often need a 'higher sleep pressure,'" Hamm told DW.
For them, taking naps during the day is a strict no-no.
"This upsets the sleep-wake rhythm," Hamm stressed.
At the same time, the regularity of sleeping times is an important prerequisite for healthy sleep, the somnologist explained. Even the midday nap, which is restorative for good sleepers and corresponds to a natural biological midday low, tends to do harm here.
According to a NASA study, a short nap, often called a power nap, can increase reaction speed and concentration. However, other studies have found that multiple daytime naps can have a negative impact on health because they are not in keeping with human nature. Humans are naturally active during the day. The day-night rhythm is controlled by hormones. During the daytime phase, the stress hormone cortisol increases, and during the nighttime phase, the sleep hormone melatonin increases. Many researchers consider a good night's sleep to be more restful overall than the plan sleep coach Nick Littlehales developed for Ronaldo, which includes napping during the day.
Hans-Günter Weess, head of the Interdisciplinary Sleep Center at the Pfalzklinikum in western Germany, is among the researchers who have called Littlehales' model into question.
"I very much assume that Ronaldo has never applied these sleep cycles," Weess told German public broadcaster SWR. "Otherwise, his athletic performance would not be what we have observed in recent years."
In fact, as is the case in all aspects of mental training, the impact of sleep training on performance is difficult to measure. In sports, the only measure that counts is the degree of success on the field of play.
This article was translated from German