(Inside Science) -- As the world's fiercest competitors gather this week in Rio de Janeiro for the Olympic Games, athletes and coaches will use every strategy they can to gain an edge. But according to many experts, the most important thing for boosting athletic performance -- and shaving a second or two off a world record -- isn't a sleek uniform, the best shoes or a high-carbohydrate diet: It's sleep.
"I think sleep gets the shorter end of the stick, when we all, athlete or otherwise, have competing priorities," said Norah Simpson, a sports scientist at Stanford University who studies the role of sleep on athletic performance. And athletes at the Rio Olympics will have to fight to get enough of it, thanks to events at unusual times, international travel and, of course, the stress of competition.
As a population, athletes often have poor sleep quality and quantity, according to Simpson. Research also shows that when people are tired, they're not very good at judging their own alertness or ability to compete. But sleep is one of the simplest enhancements an elite athlete can make to his or her performance. Simpson says some athletes still view tolerance for insufficient sleep as a badge of honor, but many are starting to realize that rest can mean the difference between winning and losing.
"Instead of the attitude, 'I can get by with little sleep,' this is really the opposite perspective, where people are really touting the importance of sleep and their prioritization of it," she said.
The Jamaican sprinter Usain Bolt, widely regarded as the fastest person ever timed, plans to defend his titles from 2012 and 2008 at this year's games. He has said, "Sleep is very important to me." NBA star LeBron James says he gets 12 hours of shut-eye a night. And professional sports teams from every major league are increasingly hiring sleep coaches and working with sleep scientists, Simpson says.
"It's been nice to see athletes speaking about the importance of sleep in their own athletic performance, and how much they value their sleep," she said. "Although, do I expect that has filtered down so that all athletes are really assessing and prioritizing optimal sleep patterns? Probably not."
They should, at least to a degree, said Nick Littlehales, a sports sleep coach in England who is working with the British national cycling and track teams. He tries to teach athletes to include sleep as just another performance factor, like recovery, training and diet, but he cautions against over-analysis.
A typical sleep cycle lasts about 90 minutes, and it includes five phases of sleep: about an hour of non-rapid-eye-movement (REM) sleep, and about half an hour of deep REM sleep, in which we dream. Littlehales encourages athletes to think about a night as a collection of 90-minute cycles.
"If I'm working on a five-cycle routine, I look at the seven days in front of me. What I'm looking for are 35 slots to get 35 cycles in. It may be that my schedule is three or four at night, and one midday nap," he said. "You can start to play around a little bit."
This approach can benefit anyone whose schedule forces a shift from his or her natural circadian rhythms, Littlehales said. That can include athletes traveling to different time zones, and people accustomed to competing at different hours of the day.
In 2013, Roger Smith of Brigham and Women's Hospital in Boston found West Coast NFL teams may fare better in evening games against East Coast teams, simply because according to their bodies, it's still early in the day. That said, jet lag, or falling out of sync with the daily cycle of the sun, is notoriously more difficult when traveling east versus west. This is partly due to different oscillations in a certain type of brain cell that controls circadian rhythms, according to research published last month in the journal Chaos. In Rio, the upshot is that athletes from the western U.S. may have a harder-than-expected time adjusting to the new time zone, and should have arrived even earlier to allow enough time to adjust.
Even after they get over the jet lag, athletes will still be competing against their own natural cycles: Some people are morning larks, and others are night owls. This could be problematic for athletes used to training in the morning, but who will find themselves competing late at night. For instance, swimmers often train in the early hours, but the finals for most races are scheduled for the late evening to accommodate prime-time TV schedules, Littlehales said.
Simpson, Littlehales and other sleep experts say the right lighting can also make a difference. Using sun-like lamps can help reset the circadian clock, fighting jet lag and boosting hormones like cortisol to help athletes stay sharp. On the flip side, warmer wavelengths of light at night can promote the production of melatonin, a hormone related to darkness and sleep. Littlehales also advocates turning off electronic devices at night.
He says he toured the Olympic Village several months ago, and was unimpressed by the quality of the beds, so he shipped 30 "sleep kits" to Brazil in March to make the stay more comfortable for the athletes he works with. The kits include gel mattress toppers, sheets, air filters and humidifiers.
"We will make that environment the best possible for those athletes, even understanding the pipes might be leaking," he said, referencing a complaint from the Australian national team about conditions in the Village. When victories are often measured in fractions of a second, a more comfortable bed and a good night of rest may make the difference, he said.
"We've done everything in our power to help that athlete compete in those conditions. We don't send them in there unarmed."