Your parents probably warned you about the dangers of not getting proper rest. Decades of research by scientists who study sleep have been showing that they were right.
While retaining information and staying awake in class or while at work is important, the research makes it clear that proper sleep has extensive benefits to physical health, too. During the recovery period from exercise, these benefits can be profound.
Sleep and Exercise: A Two-Way Relationship
Researchers have firmly established that sleep and exercise have beneficial effects on each other. The more high-quality sleep you get, the better athletic performance you are likely to achieve; the more regular exercise you get, the better your sleep quality is likely to be.
Unfortunately, many Americans don't take advantage of this recovery/performance relationship.
Check out these statistics from the Centers for Disease Control and Prevention (CDC):
- over one-third of American adults sleep less than seven hours per night
- two-thirds of high school students get less than eight hours of sleep on school nights
- the percentage of adults who do not exercise regularly have risen from about 15% in 1988 to nearly 50% in 2010
How Sleep Affects Exercise Recovery and Performance
For those who do engage in exercise, nowhere are the benefits of sleep more apparent than in post-exercise recovery. Scientists have been studying the effects of sleep on the body's recovery from exercise for nearly 40 years!
Here are the most established benefits of sleep as it relates to exercise:
● Improved mood
● Increased aerobic tolerance
● Higher stamina
● Faster muscle recovery
● Increased lean muscle mass
● Lower levels of stress hormones
● Healthier immune system
Collegiate and professional sports organizations have long been interested in the health benefits of sleep on athletic performance as they look to maximize the potential of their elite athletes.
Stanford University's sleep researchers conducted a study looking at increased sleep and their basketball team. They found that sleep about 10 hours per night, their basketball players increased their free throw and 3-point shooting percentages by a whopping 9 percentage points each. Not to mention, they also improved wind sprint performance and stamina!
Another study from the Stanford sleep lab showed that when playing at home, NFL teams based in the Mountain or Pacific time zones were twice as likely to "cover the spread" when facing Eastern opponents in the late afternoon or at night. Why? For the Eastern teams, these night games would often end around 2 or 3 a.m. Eastern time. A time when most would usually be sound asleep!
These two studies shed light on the importance of sleep quantity as well as abiding by our internal circadian rhythms.
Quality and Quantity Both Matter
Other research demonstrates that while the quantity of sleep is clearly an important factor in exercise recovery, sleep quality may be an accurate predictor of bone and muscle health.
Sleep quality also has a two-way relationship with exercise: the better the sleep quality, the better the performance. The reverse is also true: exercises of all types of intensities help improve quality of sleep.
Factors that Affect Sleep Quality
Perhaps you get adequate exercise and have made efforts to get eight hours of sleep, but you still feel tired or weary. It could be that you aren't achieving the deeper stages of the sleep cycle. Typically, frequent interruptions during the night keep us from a deep sleep. Examples include noise, over-hydration (i.e., bathroom trips), and a partner who snores.
- Frequent interruptions: Many factors can interrupt sleep, like noise, over-hydration that causes nighttime bathroom trips, stimulants like caffeine or light, and a partner who tosses and turns throughout the night.
- Reduced oxygen delivery: It might sound odd, but airways can be blocked while sleeping. When blocked, oxygen exchange in the lungs becomes poor and trips the brain's alarm system to wake up and breathe. This process repeats itself, sometimes hundreds of times per night. For more information, learn more about obstructive sleep apnea here.
- Medications: Some medications reduce the amount of time your body spends in the deeper stages of sleep. This deprives the body of this restorative rest period, making it easier to be awakened at night. Stimulants and several other medication classes decrease the "arousal threshold" — the amount of stimuli it takes to awaken you from sleep.
- Screen usage: A decade of research has shown that those who use screens in bed consistently experience poorer sleep than those whose bedtime routines are absent of screens. These results hold especially true for children and adolescents.
Research suggests that the body manufactures and releases testosterone and growth hormone in the most during periods of deep sleep. These two hormones are critical for the proper repair and functioning of bones and muscles, especially after exercise. They are also most responsible for burning fat and increasing lean muscle mass.
Getting adequate sleep, both in duration and in quality, is essential to maximizing exercise recovery. Don't worry, though — you can still tell mom that you're doing it to improve your math skills.