The reason why sleep is so important is because it allows the brain to recover from the stress of the day. According to research insufficient sleep has been linked to increased risk of obesity, heart disease and psychological issues like depression. Exercise and sleep have a more complicated relationship than many people realise. While you sleep, amazing things are occurring in your body such as Growth Hormone (GH) production; which is largely responsible for tissue growth and repair. In this week’s article find out why optimal sleep is absolutely essential for anyone who exercises regularly.
To sleep or not to sleep?
Previous studies have suggested exercise can help people with sleep problems and it was believed a good workout that makes you more tired and can send you straight to sleep. However, according to a number of recent studies, it now appears the reverse is true. Many people struggle to fall asleep after a hard workout session and the physiological explanation is still not fully understood. In fact, these studies show that the more active people are during the day, the less they sleep in the night; although this may be explained by the different personality types. Active and ambitious individuals may also be more hyperactive at night and therefore sleep less. Meanwhile, less active people may have no difficulties falling or staying asleep. Another common explanation is that life stresses lead to busier days, more exertion and may interfere with sleep.
Why could exercise make people sleepy?
Exercise improves sleep because it produces a rise in body temperature, which is then followed by a drop a few hours later. It is the drop in temperature which apparently makes people sleepy. In addition, there have been conflicting opinions as to whether morning or afternoon exercise is better. The traditional advice has been to exercise at least three to four hours before bedtime to give the body enough time to cool down and avoid having a hard time falling asleep. But given the latest research results, scientists may have to think again. Vigorous exercise right before bed stimulates your heart, brain and muscles and also raises the body temperature which is the opposite of what you want at bedtime. When it comes to having a direct effect on getting a good night’s sleep, it’s cardiovascular exercise in the late afternoon or early evening that appears to be the most beneficial. That’s because there is enough time for body temperature to fall down to normal levels before bedtime.
Hormones & Sleep
Consistently getting inadequate sleep can result in subtle changes in hormone levels, particularly those related to muscle recovery, stress and mood. Research suggests that sleep deprivation can lead to increased levels of cortisol (a stress hormone), decreased activity of human growth hormone (which is essential during tissue repair), and decreased glycogen synthesis. Glucose and its stored form, glycogen, are the main sources of energy. Sleep deprived individuals may experience slower storage of glycogen, which prevents them from responding to heavy training, and also interferes with tissue repair and growth.
Athletes or people who train on a daily basis need at least 8 hours of sleep each night and maybe even a nap during the day. One of the hypotheses as to why, especially endurance, athletes sleep so much is the cytokines hypothesis. Exercise prompts muscles to release two cytokines (hormones), interleukin 6 and tumor necrosis factor alpha that make people drowsy and prolong the duration of sleep. Increasing the duration and intensity of exercise has been linked to an increase in the release of those two hormones. Interestingly, those cytokines are also released when people have a cold or an infection, which explains why we usually feel the need to sleep more when we are ill.
Rest & recovery
Rest and recovery is an essential part of any workout routine as it has a great impact on fitness gains and sports performance. So what happens during this period that is so important? First of all, rest after a hard workout allows the repair and recovery process to happen at a natural pace which is essential for muscle and tissue repair and strength building. Moreover, this is the time that the body adapts to the stress of exercise and the real training effect takes place. Recovery also allows the body to replenish energy stores (muscle glycogen) as well as fluid loss, and repair damaged tissues. This is also the time for the removal of chemicals that build up as a result of cell activity during exercise (exercise induced oxidative damage). Without sufficient time to repair and replenish, the body will continue to breakdown from intensive exercise and overtraining will occur which causes depression, decreased sports performance and increased risk of injury.
Short and Long-Term Recovery
There are two categories of recovery; the immediate (short-term) recovery from a particularly intense training session or event, and the long-term recovery that needs to be built into a year-round training schedule. Both are equally important for optimal performance.
Short-term recovery, often called active recovery, occurs in the hours immediately after intense exercise. It refers to engaging in low-intensity exercise after workouts during both the cool-down phase immediately after the session as well as during the days following the workout. Both types of active recovery are linked to performance benefits. Another major focus of recovery immediately following exercise has to do with replenishing energy stores and fluids lost during exercise and optimizing protein synthesis and this is where post-exercise nutrition comes into play.
Although, more research is necessary to understand the complicated relationship between exercise and sleep, it is true that exercise can help you sleep sounder and longer and feel more awake during the day; A chronic lack of sleep may affect metabolic function. The key is the type of exercise you choose and the time you do it during the day. Exercising vigorously right before bed or within about three hours of your bedtime can actually make it harder to fall asleep. On the other hand, morning exercise can relieve stress and improve mood. A good advice is to try and schedule at least 20 minutes of vigorous exercise three or four times a week. Of course you can choose any activity you enjoy: jog, bike, swim, dance etc. It can be anything as long as you make it part of your daily routine. And remember to add a recovery plan and a healthy and balanced nutrition.
By Kleio Bathrellou
Associate Nutritionist & ISSN Certified Sports Nutritionist