I left my running shoes at home when I packed for my recent vacation on an Italian island. (Can you blame me?) After a week of eating molto gelato and floating on my back in the Tyrrhenian Sea as my chief form of exercise, I expected my first run back in Brooklyn to be a death march. Instead, I felt the best and went the fastest that I have in weeks. One possible explanation came to mind: I erased my chronic sleep debt on vacation, thanks to sleeping in as long as I wanted in the mornings and napping most afternoons, which made me extremely well rested when I took that run.
Sleep, as sports performance coach Mark Verstegen told me last fall, is a "magic pill." That message is often ignored by athletes who think it's better to train for another hour or two rather than spend that time snoozing. In that way, they're just like everyone else. "Our society is not built around getting a lot of sleep," says Cheri Mah, a researcher at the Stanford Sleep Disorders Clinic and Research Laboratory. "A lot of people see it as a waste of time." Not surprisingly, there are a lot of people—athletes and nonathletes—walking (or running, as the case may be) around with a sleep debt. (My colleagues at U.S. News have written previously about how to get a good night's sleep and why kids need sleep even more than the rest of us.)
For the rest of us, sleep debt may mean drowsiness during the day, crabbiness, and brain fog. For athletes, it can translate into all that plus diminished performance and recovery. Mah recently presented a small study looking at the effects of sleep on competitive swimmers' athletic performance and mood. Five Stanford University swimmers were assessed first after keeping their regular sleep habits and then after sleeping 10 hours a day for a number of weeks. After getting more sleep, they were quicker off the blocks, faster in the water, and had speedier turns. And they reported better moods and less fatigue, Mah told other researchers at the annual meeting of the Associated Professional Sleep Societies in Baltimore. Last year, she reported similar results after a small study of Stanford basketball players.
There hasn't been much specific research on athletes, says Charles Samuels, the medical director of the Centre for Sleep and Human Performance in Calgary, Alberta. (The field is relatively new, plus it's hard to get elite athletes to agree to the sleep deprivation that experiments require.) What we know about sleep, health, and human performance comes mostly from research in the military and in the transportation and aviation industries, where sleep problems have obvious and potentially deadly consequences, Samuels says. It's clear that during slow-wave sleep, when your sleep is deepest, specific metabolic processes occur that promote recovery from the last workout—key for endurance- or power-based sports, like running, biking, and weightlifting. Research also suggests that REM (rapid eye movement) sleep is critical for memory consolidation and for embedding a task or skill, he says. That's important for athletes in skill-based, precision sports (think basketball, swimming, and shooting).
The guidelines for daily sleep range from about seven to nine hours for adults and nine to 10 hours for adolescents and teens, says Mah. But to find out how much sleep you personally need, estimate your ideal sleep period based on how you feel given your current amount of sleep and experiment over a few weeks. You're in the ballpark if you can go to bed and fall asleep in about 20 minutes (and not a lot sooner, which may suggest sleep debt), then wake up spontaneously, without an alarm, she says. You also shouldn't be excessively groggy in the morning and shouldn't be fatigued during the day. Keeping a sleep journal can help you recognize patterns.
It can be tough to get as much sleep as you need at night, so you can supplement with strategic napping, says Samuels. Limit naps to no longer than 30 minutes. The natural time to nap is about 12 hours from the midpoint of your longest sleep cycle. If you sleep from 11 p.m. to 7 a.m., that would mean a nap at about 3 p.m. Unfortunately for athletes, that's often smack in the middle of scheduled workout time. (Unfortunately for everyone else, napping isn't generally acceptable workplace behavior.)
If you are an athlete, Mah advises you to gear up for a competition by extending your sleep in the weeks before. And try to go to bed and wake up at about the same time every day. It all sounds like a luxury I usually get only on vacation, but if I can improve my running performance, I'm willing to make an effort.