Sleep: The ultimate recovery tool and performance enhancer
By Anne Linton MD
As an athlete you are always looking for ways to improve your performance and recovery so you can train harder and get faster. You have access to great coaching with training plans, nutrition secrets, and strength training, to name a few. But you are always looking for a way to get that extra edge on the competition. There is an easy, cheap and legal way to improve your performance: get more sleep!
According to the American Academy of Sleep Medicine, increasing one’s sleep can increase athletic performance. Cheri Mah at Stanford Sleep Disorders Clinic and Research Laboratory has been studying sleep and athletic performance for many years. Over the years she has done studies with the Stanford men’s and women’s swim teams, women’s tennis, and men’s basketball, football, track and field teams looking at the effects of increased sleep on athletic performance. These studies showed that after anywhere from 5-7 weeks of extending one’s sleep to 10 hours a night, all the athletes showed improvements in their performance, mood and alertness.
In particular, the swimmers swam a 15 meter sprint 0.51 seconds faster, reacted 0.15 seconds quicker off the blocks and improved their turn times by 0.10 seconds and increased their kick strokes by 5.0 kicks. Mah also noted that many of the athletes in this study have set multiple new personal records and season best times, as well as broken long-standing Stanford and American records while participating in the study. Even those athletes who were unable to comply with 10 hours of sleep per night showed improved performance with just an increase of 30 minutes of sleep a night.
What does sleep do that can improve performance? During slow wave sleep (deepest sleep) there are specific metabolic processes, which occur that help us recover from our workouts. This includes the release of human growth hormone, which helps to promote recovery, and regeneration and helps to build lean muscle mass. In addition, sleep is essential to glucose metabolism, which replenishes our glycogen stores for the next day’s workout. Research also suggests that REM (rapid eye movement) sleep is critical for memory consolidation and for embedding a certain task or skill learned during the day. Researchers at Harvard Medical School, Matthew Walker PhD and Robert Stickgold, PhD, have done sleep and chronobiological studies looking at learning and have found that after initial training, the human brain continues to learn in the absence of further practice. This improvement develops while you sleep.
So how much sleep do we need?
A study done in 1994 by the National Institute of Mental Health had subjects stay in bed in the dark for 14 hours every night for 28 consecutive nights. Initially they slept as much as 12 hours a night, suggesting they were sleep deprived and then by the fourth week their sleep stabilized to a nightly average of 8 hours and 15 minutes. In general, it is recommended adults get 7-9 hours of sleep a night while adolescents need at least 9 hours of sleep due to the growth process. Individuals who are more active tend to need more sleep. A general rule of thumb is if you fall asleep within 20 minutes and wake up spontaneously you have the right amount of sleep.
Now, most of the athletes I work with have busy lives with jobs and families, find they have to set an alarm to get up in the morning and often times get less than the recommended amount of sleep. What can they do in addition to trying to eke out just a few more minutes per night? Studies have show that sleep deprivation can be improved by strategic napping throughout the day. It is recommended to limit your naps to 30 minutes and the natural time to nap is about 12 hours from the midpoint of your longest sleep cycle. If you sleep from 11 pm to 7 am that would mean around 3 pm would be the best time to nap. Unfortunately that may not always work for the average working person, but the point is that even a short nap can be very beneficial.
Understanding the process of sleep and the causes of sleep deprivation
Sleep is governed by both homeostasis (the body’s process of self regulation) and as a direct result of a circadian biological clock (the 24 hour system the body obeys due to external cues such as daylight). In terms of restorative processes, when the body is subjected to a very demanding period of activity it will seek homeostasis by wanting to get a good sleep to recover. Also circadian rhythms tell the body when to be alert and when it should sleep. This is under the control of the hypothalamus, a part of the brain that also controls hormonal release, body temperature and how the body responds to light and darkness. Jet lag, for instance, can affect a person’s sleep.
Other things that can interfere with a good night’s sleep are alcohol (it creates an artificial desire to sleep as a depressant but often causes wakening later, before adequate sleep has been achieved), caffeine or other stimulants, medications, anxiety, snoring or other medical conditions, high intensity exercise or large meals less than a couple hours before bedtime, and napping within 3 hours of bedtime, just to name a few.
So, what happens when athletes don’t get enough sleep?
Lack of sleep can adversely affect athletic performance from both a physical and psychological perspective.
Psychologically, sleep deprived athletes have an increased rate of perceived exertion as well as an increased feeling of fatigue. The disruption of the sleep/wake cycle can also increase release of cortisol as well as lead to mood swings, irritability and depression.
From a physical perspective sleep deprivation can be detrimental to athletes on multiple levels. First of all, the cognitive impairment that results from sleep deprivation can lead to impaired motor function or delayed reaction time (both visual and auditory) for that athlete. In addition, metabolic consequences of sleep deprivation all can contribute to diminished performance. The decreased secretion of human growth hormone will diminish regeneration and recovery as well as diminish the production of lean body mass.
The effect of sleep deprivation on glucose metabolism can lead to decreased storage, conversion and metabolism of glucose leaving the athlete with limited glycogen stores for the next day’s workout as well as place them at risk for diabetes and weight gain. This can happen on as little as 7-10 days of limiting sleep. A consistent lack of sleep has been shown to reduce cardiovascular performance with some studies showing as little as 30-36 hours of sleep deprivation resulting in a loss of performance. Increased production of cortisol, a stress hormone, happens with sleep deprivation. Cortisol has many negative effects to an athlete including diminished recovery, decreased immune functioning, increased fat storage and negative mood changes in the athlete.
As you can imagine, the combination of these physical and mental factors can increase the risk of injury to a sleep-deprived athlete. As well, overtraining can occur with a much smaller volume or intensity of training in sleep-deprived individuals.
The medical consequences of sleep deprivation
According to sleep researcher and professor of psychiatry at Stanford University, William Dement, M.D., Ph.D., a chronic sleep restriction, which is widespread among American adults, has serious adverse consequences for physical and mental performance. He reports that sleep loss is cumulative and refers to this phenomenon as “sleep debt.” He explains that the brain records as a debt every hour of sleep that is less than a person’s nightly requirement. This snowballing debt may include an hour of sleep lost a week or month ago, as well as the hour lost last night. A large sleep debt can only be reduced by extra sleep.
At the American College of Sports Medicine’s 12th-annual Health & Fitness Summit & Exposition in March 2008, William G. Herbert PhD, FACSM presented information on the effect of sleep and sleep deprivation in the fitness field. He reported that one quarter of all people have some form of a sleep disorder with only 50% of those being diagnosed. He reported that sleep is important in regulating appetite and metabolism, in particular glucose metabolism. He reported those who are sleep deprived over time overeat and gradually gain weight. In turn, those that are overweight are more at risk for Sleep Apnea syndrome, a disorder where individuals can wake up to 100 times a night “gasping for air.” Eventually, this can lead to a chronic lack of energy, lack of motivation for exercise, high blood pressure, and depression — all things that can decrease ones ability to engage in an exercise program.
Considerations for sleep and training
So, next time you think about getting up earlier to fit in that extra workout, think about it in terms of the risk to benefit ratio. Am I getting enough sleep? Will that extra workout really make that much of a difference in my overall training if I am sleep deprived? Most of the time a good night’s sleep will do you more good in your overall training regimen than an extra early morning workout in lieu of a good night’s sleep.
Here are some recommendations for getting a good night sleep and for sleep habits for athletes:
· Maintain a good amount of sleep regularly aiming for 7-9 hours a night so as not to develop sleep debt
· Gear up for competition by extending your sleep the weeks before the event (and remember the Stanford athletes who improved significantly on 10 hours a night )
· Try to go to bed and wake up the same time every day
· Don’t eat heavy foods right before bedtime
· If you can’t get a good night’s sleep, try to take naps but don’t nap within 3 hours of your bedtime
· If you have chronic daytime fatigue or you are a known snorer, get a medical evaluation
· Don’t do any high intensity exercise right before bedtime
· Don’t watch TV in bed
· Limit the use of alcohol
· Limit use of caffeine during the afternoon/evening
· Don’t sacrifice sleep for “one more workout”
June 2008 “Ongoing Study Continues to Show that Extra Sleep Improves Athletic Performance “)
C. Mah. Study Shows Sleep Extension Improves Athletic Performance and Mood. Annual Meeting of the Associated Professional Sleep
Societies. June 8, 2009.
From sportsmedicine.about.com http://sportsmedicine.about.com/cs/conditioning/a/aa062800a.htm
American College of Sports Medicine www.ACSM.org