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Medically Reviewed by Dr. Jenny Iyo
Human growth hormone (often abbreviated HGH or hGH, or simply GH for growth hormone) is a complex protein produced by the pituitary gland in the brain and is an important part of the body’s endocrine system. It is especially active in the growing child’s maturation (although it is not the only physiological factor that makes kids get taller and grow). HGH is released by the brain into the bloodstream during sleep, and its release is part of the repair and restoration function of sleep.
Sleep and exercise have a relationship similar to the chicken and the egg: they’re inextricably linked with each other, thanks to the human growth hormone.
Human growth hormone (often abbreviated HGH or hGH, or simply GH for growth hormone) is an important part of the body’s endocrine system. It is especially active in the growing child’s maturation (although it is not the only physiological factor that makes kids get taller and grow). HGH is released by the brain into the bloodstream during sleep, and its release is part of the repair and restoration function of sleep.
The hormone is a complex protein produced by the pituitary gland in the brain, and in addition to promoting growth in childhood, it helps maintain healthy bodily tissue even during adulthood. The pituitary gland releases growth hormone non-continuously – the release looks like a pulse.
Human growth hormone promotes a healthy metabolism, enhances your physical performance, and may even help you live longer.
Both sleep and exercise induce the release of human growth hormone. Experts estimate that as much as 75 percent of human growth hormone is released during sleep.
In normal healthy people, the major period of HGH release occurs during the first period of Stage 3 sleep stage during the night, about an hour after you first fall asleep. Stage 3, also known as deep sleep or slow wave sleep, accounts for about one-quarter of your sleep each night. Deep sleep is the most restorative all stages of sleep. During this stage of sleep, HGH is released and works to restore and rebuild your body and muscles from the stresses of the day.
A person cycles through the stages of sleep four to five times each night. HGH is released during the first few times you experience stage 3 sleep. Sleep deprivation has a big impact on your sleep cycles, and consequently impacts how much, if any, of your HGH gets released during your initial cycles of stage 3 sleep.
If a person stays up all night when he or she normally sleeps, there is no surge in growth hormone release. After a period of sleep deprivation, there is extra hormone released when sleep is resumed, and the pattern departs from the normal pulse during slow-wave sleep.
Scientists did an experiment where they hid people away from daylight and other environmental cues that act as circadian hooks. The subjects were allowed to set their own sleep schedule which ended up deviating from the typical 24-hour cycle. This experiment has been done many times, but in this case the scientists measured the blood levels of growth hormone and followed when the pituitary gland released the hormone. They found the peak levels of hormone released during sleep decreased significantly. The first slow wave sleep (SWS) period of the night was shorter and the first REM period happened sooner.
The researchers concluded that the timing of sleep stages can change the amount of hormone released during sleep.
The production of HGH levels peaks at your youth, and steadily declines with age. Seniors in particular spend less time in deep sleep, which explains the link between lack of HGH and other disorders associated with aging. For example, lower HGH levels correspond with higher risk of heart disease, obesity, and diabetes.
HGH production decreases with age. In middle age, the brain starts producing lower quantities of growth hormone. People may also suppress normal HGH production due to sleep deprivation or disruption. Both normal age-related reduction in HGH levels, as well as that caused by lack of sleep, cause side effects such as weight gain, lowered cognitive and physical performance, reduced muscle mass, and other effects associated with aging such as thinning hair and higher risk of diabetes and heart disease.
HGH’s association with anti-aging properties have spurred interest in the use of supplemental hormones to keep the body young. Market grew to quickly meet the demand with an abundance of HGH over-the-counter products, supplements, creams and pills. However, the effectiveness of many of these is not widely accepted by credible medical authorities, and is not approved by the FDA.
HGH is not contained in a pill or cream, so don’t be fooled by deceptive packaging. You should also be careful of injecting yourself with synthetic forms of HGH unless you’ve spoken with a doctor. In fact, injecting yourself without a prescription is illegal and potentially dangerous.
Elite athletes sometimes use HGH supplements (such as the recombinant form called somatropin) with an eye toward improving performance. This use breaks the rules of many or most leagues and sporting authorities. It is similar to the use of steroids. Responsible doctors always oppose steroid use for performance edge because of the side effects. The side effects of growth hormone may not be as dangerous, but the medical community still looks down on this practice.
However, the connection between HGH and sleep coupled with the connection between good sleep and enhanced athletic performance are too similar to be coincidental. In fact, sleep itself is critical for athletic performance, and multiple studies have shown increased sleep (up to 10 hours) improves reaction times and speed for many sports. Smart trainers and world-class athletes understand the importance of regular sleep for optimal athletic performance.
Elite athletes often suffer problems such as jet lag due to domestic or occupational schedules that do not permit normal sleep schedules. Endurance athletes often have a problem with immuno-suppression and chronic reduction in sleep can contribute to this. Indeed, even in non-athletes, sleep deprivation can suppress the immune system.
Human growth hormone has gained an undue bad reputation due to its abuse by some professional athletes who use its synthetic form along with anabolic steroids. However, HGH helps children who suffer from deficiency, and it can also help you naturally counteract the effects of aging, as long as you promote its natural and healthy production.
The best way to increase your HGH levels is by following good sleep hygiene and getting high-quality sleep on a regular basis. High-quality sleep for most adults means uninterrupted sleep for 7 to 9 hours each night.
In addition to following a consistent sleep schedule, you should also exercise regularly in order to promote HGH secretion. Pulses of HGH are released during the day and can be affected by lack of exercise and an unhealthy diet. Exercise in turn promotes quality sleep by expending your energy.
One of the best ways to promote HGH secretion through exercise is with high-intensity interval training.
As for diet, you should think of HGH and sugar as opposites. The higher your insulin levels (from intake of high-sugar food and beverages), the lower your HGH levels. High blood sugar inhibits your HGH production, so you should avoid foods high in sugar generally, but especially before bed, if you want to avoid inhibiting your natural HGH production during sleep.