More and more athletes—from ski racer Mikaela Shiffrin to mountain bike phenom Lea Davison—are making sleep a priority in their training cycles. Here’s why you should too.
BY LEE STANTON, P.T.
With all the daily demands we encounter, finding time to exercise is challenging. Many people stay up late or get up early to exercise. If you’re entering your last block of training for the Vermont City Marathon, or getting ready for gravel racing season, maybe you fit this profile.
Here’s why sleep and rest may be just as important as your training regimen.
When you go to sleep, your body is actually still pretty active. Sleep is when our body repairs the damage we have done throughout the day. This repair is what allows us to appreciate the gains we make from our workouts. Without adequate sleep, even the best workouts are ineffective. Ironically, overtraining results in increased sleep disturbance and increases the frequency of illness.
How Your Body Uses Sleep
Sleep can be broken into four stages. Each of the first three phases (Non-REM sleep) takes 5-15 min. The fourth phase, (REM) starts at about 10 min in duration and increases to up to 60 minutes over the course of the night. Sleep then cycles through these four phases throughout the night. Of most importance to us is phase 3. During this phase, the body releases Human Growth Hormone (HGH).
HGH helps with bone and muscle repair and reduces the immunosuppression commonly seen with endurance athletes. Athletes who are sleep-deprived see reduced HGH levels and increased cortisol levels. Cortisol is a hormone that helps us manage stress. It increases blood glucose to allow the body to respond to a stressful response and suppresses the reproductive and digestive systems. Elevated cortisol levels are associated with increased abdominal fat gain, immunosuppression and cognitive decline.
Sleep is important in determining the balance between ghrelin and leptin, the hormones which tell us when we are hungry and full. Lack of sleep can result in poor glycogen (carbohydrate) storage and may make carbo-loading ineffective. Inadequate stores of carbohydrate can make long runs harder and result in you “hitting the wall” earlier on race day. Chronically sleep-deprived athletes present with impaired glucose metabolism and insulin resistance. Insulin resistance is a precursor to diabetes.
Hydration balance is restored via water resorption and regulation while sleeping. During the night, our kidneys work to balance water, sodium, and electrolytes. Exercise stresses our hydration status and these values can take a little extra time to achieve balance. This effect is magnified in the summer when dehydration can be increased with increased sweat rates. Chronic dehydration causes muscle pain and reduced performance. Dehydration can occur in one bout of exercise, or progress slowly over several days.
Better Sleep, Better Racing?
Many studies have shown the benefits of increased sleep on performance. Some coaches like to point out that the benefits of a workout are only realized during the recovery. If the body never recovers, your fitness never improves. Logging a little extra sleep time in the weeks leading up to your marathon can pay off both in reduced injury risk and improved performance leading up to your race.
VO2 max is generally considered a measure of fitness as it is a measure of your body’s ability to exchange oxygen. While VO2 max does not change with one sleepless night, it is has been shown to drop after two. Peak HR also decreases after several days of insufficient sleep.
Research indicates that the average adult needs 7-9 hours of sleep per night. Since the 1960s, the average time spent sleeping per night has dropped from 8.5 hours per night to 7.5 hours per night.
Getting less than six hours of sleep per night can be damaging to your genes. A study showed seven nights of sleep deprivation resulted in a number of genetic transcription changes with consequences ranging from obesity to heart problems. Individuals who get less than six hours of sleep have 50 percent less immunity protection than those getting eight hours of sleep per night.
Another study showed that getting less than six hours of sleep increased the risk of stroke, increased appetite, increased risk of diabetes, increased memory loss, increased cancer risk, increased osteoporosis, decreased sex drive, increased depression and increased risk of dying at a younger age.
Determining the Right Amount of Sleep for You
Determining if you are getting enough sleep is easy. If you wake up feeling tired and groggy, you are not getting enough sleep. If you hit the snooze button repeatedly on your alarm, you are not getting enough sleep. Appropriate levels of sleep should result in you waking up feeling refreshed, rested, and ready for the day.
There are two ways you can determine how much sleep you need. The first is a sleep test. While on vacation (ideally at home, to minimize issues with different beds, time zones etc), go to bed at your normal time. Fall asleep without an alarm. Sleep until you wake feeling fully rested. It generally takes about four days to recover from sleep deprivation. On the fifth day, see how much sleep you get and this should be your goal.
If you aren’t able to use the sleep test noted above, another rule some runners will use is eight hours +miles/week in min. So, if you are running 30 miles per week, then your time spent sleeping would be eight hours and 30 minutes a night.
Training and Rest
In the weeks leading up to the race, it is common for anxiety to cause sleep disturbances for many athletes. Studies have shown that athletes who are sleep-deprived are capable of running extended distances, but they also rank the cognitive demand of the event as being higher. They also demonstrate increased moodiness, anxiety, and irritability.
In the final weeks of training and into the pre-race taper, some athletes channel their anxieties into busywork or even trying to squeeze last workouts in. The takeaway message of this article is that sometimes you can get more out of rest and sleep than from logging a few extra miles.
After an event, athletes can be tired, but sometimes the efforts of the day result in discomfort and restlessness at night. On average, marathon runners sleep an extra hour per night for four days after a marathon and two hours per night for a week after completing an ironman. I find a steady intake of fluids after a big event can help keep some of the achiness at bay and help provide a more restful night of sleep after a big effort.
Best of luck on race day, and I’ll see you on the roads.
Lee Stanton, PT, is a physical therapist at the UVM Medical Center’s Orthopedics and Rehabilitation Center. He specializes in running mechanics and running-related injuries as well as multi-trauma injuries and total joint replacement. He is a father of two children and personally familiar with the effect of fatigue on running performance.