As an athlete, I train hard. I put myself through grueling workouts, I eat right (mostly), and I do the extras—strength work, stretching, massage, mental training. I get up at the crack of dawn to put in the extra miles before a full day of work and parenting. What if one of the keys to athletic success, however, is one I’ve been neglecting all this time? Could sleep deprivation be limiting my athletic performance? If so, could some extra ZZZs make a difference in my next race? I ponder these questions as I sit with my mid-afternoon cup of joe, trying to combat the yawns before I tackle my second run of the day.

Sleep is one of the fundamental needs of our bodies yet the first to be short-changed when there aren’t enough hours in the day. Americans as a whole are sleep-deprived, and lack of sleep has been linked to a variety of health problems, including obesity, cardiovascular disease, depression, and diabetes. What some of us might not realize, however, is that sleep deprivation can significantly affect our athletic performance, too.

One recent study from the University of Chicago Medical School found that after only one week of sleep restriction, subjects metabolized glucose less efficiently and also had higher levels of cortisol. What does this mean for athletes? Simply put, less stored energy, reduced endurance, and a diminished ability to repair damaged tissue. For endurance athletes in particular, this combination is a recipe for disaster. Over time, these factors will prevent athletes from handling their training load, potentially leading to overtraining and poor performances.

Slow-wave sleep, which occurs 20-30 minutes into the sleep cycle, is the deepest part of sleep and the most important part for athletes, since this is when the most recovery occurs. During this stage, growth hormone is released from the pituitary gland, simulating muscle growth and repair, bone building, and fat burning. In short, this is the time when our bodies recover from, and adapt to, the demands of training. Short-change your body here and it will show in your performance.

Other effects of sleep deprivation include impaired motor function, delayed reaction time, and reduced cardiovascular performance—possibly by as much as 11%. Psychological effects are possible as well, including increased perceived exertion and depression.

Since most studies on sleep seem to involve participants going without sleep for extended periods of time, sometimes 24-36 hours, I wondered if the results would be relevant for athletes. Although my adventure-racing friends routinely compete in 24-40 hour events, most athletes I know don’t usually go without sleep for this long. It turns out, however, that sleep loss is cumulative. Sleep researcher Dr. William Dement of Stanford University refers to chronic sleep deprivation as “sleep debt.” He explains that the body records every hour of sleep missed from a person’s nightly requirement. This means that staying up just an hour or two later each night for a couple of weeks can result in significant impairments in performance.

Just as sleep loss can hurt athletic performance, a 2007 study conducted by Cheri Mah at Stanford University showed that extra sleep actually improves performance. She tested members of the Stanford men’s basketball team before and after a two-week period in which they obtained as much sleep as possible, observing significant improvements in their game. They ran faster and made more free throws than they did with their typical sleep schedule and reported having increased energy, improved mood, and a decreased level of fatigue.

Officials at the Olympic Training Center in Colorado Springs are aware of the importance of a good night’s sleep. Prior to the 2006 Olympic Winter Games, they brought in Dr. Mark Rosekind, a sleep specialist, to evaluate the athletes’ sleeping conditions. According to Rosekind, “Optimal sleep translates into optimal performance.” Among his recommendations are low light, cool temperatures, and minimization of background noise. He recommends 7.5 to 8 hours of sleep for most people, significantly more than the 6 hours, 40 minutes that Americans averaged in 2007.

Joe English, a marathon and triathlon coach in Portland, Oregon, recommends supplementing nighttime sleep with naps. He believes that naps can be an important part of any serious training plan, giving the body an extra chance to recover between workouts. Deena Kastor, America’s top female marathoner, must agree. I recently read an interview with her in which she describes sleeping for 10-14 hours a day, including a two-hour afternoon nap.

Obviously for those of us who do more than train and race for a living, sleeping half our lives away isn’t an option. But maybe there’s a lesson to be learned from the elites. By treating sleep as an important component in our training, rather than something that we get to after we’re finished with all of the other responsibilities of the day, we could find ourselves to be not only better athletes, but also more energetic and productive individuals.

Anne Lundblad is a mom, college counselor, and world-class ultra runner.