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Human growth hormone (HGH) is an essential component of our well-being. It is a naturally-produced substance that promotes healthy muscle and bone mass while working to regulate metabolism.
For healthy adults, sleep is a key time for the release of human growth hormone. The biggest and most significant production of HGH happens during deep sleep, and serious sleep disruptions can interfere with the body’s normal process for releasing HGH into the bloodstream.
Unfortunately, because of HGH’s reputation related to doping in sports and dubious anti-aging remedies, both of which involve synthetic and not naturally produced HGH, there is considerable misinformation about this vital hormone.
In this guide, we’ll clear things up by explaining what HGH is, how it relates to sleep, and how to naturally promote its production. We’ll also cover why synthetic HGH has been used by athletes and which medical situations are appropriate for synthetic HGH injections.
What is Human Growth Hormone?
Human growth hormone — also known as HGH, hGH, growth hormone, or GH — is a substance that is naturally produced by the pituitary gland. The pituitary gland is about the size of a pea and is found at the base of the brain. Growth hormone secreted from this gland is released into the bloodstream and serves a number of important bodily functions.
Growth hormone was initially identified based on its role in promoting growth in children, and this origin is reflected in its name. In childhood and adolescence, it has a critical function of making people grow taller and stronger. In adults, too, growth hormone contributes to growth and strength. Though adults don’t keep getting taller, growth hormone helps develop muscle mass and bone strength.
Despite its name, growth hormone also plays a part in other important biological processes. Growth hormone is directly involved in managing metabolism, which is the body’s process of converting and using energy. Specifically, growth hormone is implicated in the complicated ways in which food is converted to energy and that blood sugar and fats are regulated and controlled.
Growth hormone deficiency (GHD) is when someone does not produce enough of this hormone. Children with a growth hormone deficiency often have symptoms of reduced height, weaker muscles, a younger-looking face than other children their age, and delayed puberty. In adults, symptoms can include increased fat around the waist, reduced bone and muscle mass, thinning skin, fatigue, mood problems, and sleeping problems.
It is also possible to have too much growth hormone. For children, the result can be gigantism, a rare disorder that can cause a child to be large for their age and suffer from a range of other potential symptoms including headaches, sweating, joint pain, and weakness. In adults, too much growth hormone causes acromegaly. There are many possible symptoms of acromegaly some of which include enlarged bones, fatigue, sleep apnea, excessive sweating, body odor, and headaches.
When Does the Body Produce Human Growth Hormone?
During every 24-hour period, the pituitary gland secretes growth hormone as a result of signaling from the hypothalamus, a part of the brain directly above the pituitary. The secretion of growth hormone is intermittent; it happens through roughly 6-10 pulses during each 24-hour period.
Not all of the bursts of growth hormone are the same. The length of the pulse and how much growth hormone that is released can vary based on a number of factors. The peak burst of growth hormone typically occurs at night during sleep. Specifically, it occurs during the first period of slow-wave sleep and can account for 50% or more of the daily release of growth hormone. Further bursts can occur during later short-wave sleep periods, and in total, these bursts make up greater than 70% of daily growth hormone production.
Slow-wave sleep is also known as deep sleep. When we are sleeping, we progress through a series of four sleep stages that in total last around 90 minutes. The first three stages are part of non-rapid eye movement sleep (NREM), and the last stage is REM sleep. During the first stages, your body begins to relax and slow down, reaching deep sleep in stage III. This stage typically lasts from 20 to 40 minutes. You are much harder to wake up during slow-wave sleep, and it is believed that this stage plays an important role in the restorative power of sleep.
Sleep is important for the production of growth hormone, but it is not clear if sleep must be aligned with the local day-night schedule to have a healthy level of GH. One small study of night shift workers found that their growth hormone secretions were reduced during their period of sleep (from 7 a.m. to 3 p.m.) but that secretions during the rest of the day increased to compensate for the reduction during sleep. As a result, if a person does not produce growth hormone during the night, it does not necessarily mean that they will not be able to maintain a beneficial level of growth hormone in the body so long as they obtain enough sleep overall.
Exercise is another key factor that influences the production of growth hormone. In fact, sleep and exercise have been identified as the two most important stimuli for initiating the production of growth hormone. Exercise-induced growth hormone response (EIGR) refers to this boost in GH production that comes from certain types of activity.
The type of exercise, its duration, frequency, and difficulty level may all play a role in the extent to which the activity amplifies the release of growth hormone. Some research has focused on heavy resistance training to boost growth hormone secretion while other studies have found it to occur with both aerobic exercise and resistance training. Though exercise can spur bursts of growth hormone, longer duration of exercise or multiple bouts of exercise in a 24-hour period may be necessary to significantly increase the net daily amount of growth hormone released. Research is ongoing to better understand exactly how specific types of exercise alter the short- and long-term release of growth hormone.
While sleep and exercise are two key factors that are involved in the production of growth hormone, there are other influences at play as well. Nutrition, stress, age, and other factors related to development and metabolism can affect the release of HGH. The interrelationships between these factors can make it challenging to isolate the influence of sleep or exercise alone. Nevertheless, the research is clear that sleep, especially deep sleep, and quality exercise are critical elements of the body’s normal process for releasing growth hormone.
How Does Sleep Quality Affect Human Growth Hormone Production?
Because sleep is closely connected with the release of human growth hormone, sleeping problems can negatively affect its production. As detailed in the previous section, in healthy adults the majority of growth hormone is secreted during slow-wave sleep. As a result, people whose sleep is curtailed or whose sleep architecture is disrupted can have a diminished level of growth hormone.
One way that sleep disruptions can hinder growth hormone production is through insomnia. Insomnia is characterized by persistent problems in falling asleep, staying asleep, or both. It can be a short-term (acute) or long-term (chronic) problem, and it is estimated that insomnia affects around one-third of people in the United States. In a study of 15 people with chronic insomnia, researchers found dramatically reduced levels of growth hormone over a 24-hour period. The study participants who had detectable levels of growth hormone were those who had the fewest sleep disturbances.
Changes to the timing of sleep can also affect growth hormone production. In another study, patients were separated from any time cues and slept when they wanted. During this free sleep, they tended to have lower peak levels of growth hormone production and a shorter initial period of slow-wave sleep. A different study found that sleep deprivation altered the pattern of growth hormone release, even if that sleep deprivation was only for a short period. If a person is continually disrupted during sleep and having difficulty achieving deep sleep, it may alter the pattern by which growth hormone is released in their body.
Most of these studies are small and involve patients who are younger and otherwise healthy. This can make it hard to know exactly how sleeping problems affect the release of growth hormone in other people. Because multiple factors influence how and when growth hormone is produced, there are limits to the ability to isolate causality in this research.
In addition, it is difficult to know how changes to the timing of the surges of growth hormone affect overall health. While an overall deficiency of growth hormone can have serious symptoms in adults — reducing muscle, weakening bones, thinning hair — sleep disruptions do not necessarily translate to a growth hormone deficiency.
In a number of studies, it has been found that people are able to compensate by producing growth hormone at times other than during short-wave sleep. For example, some patients had more HGH production during the day or even during other stages of sleep. This may mean that their overall production of this important hormone stays at nearly the same level to avoid any notable deficiency. It is unknown whether there are specific health consequences to a shifted timeframe for growth hormone production.
What is known is that, under normal circumstances, growth hormone is produced predominantly during slow-wave sleep, especially its first onset each night. Given the already well-established benefits of deep sleep for rest and recovery, it makes sense to optimize your sleep and facilitate the body’s most natural tendency for the timing of growth hormone secretion.
Synthetic Human Growth Hormone
In patients who are deficient in growth hormone, one treatment can be to administer injections of synthetic growth hormone. Synthetic growth hormone may also be referred to as recombinant human growth hormone (rhGH).
As a medication, synthetic growth hormone is known as somatotropin, and brand names for it include Norditropin, Nutropin, Humatrope, Genotropin, Omnitrope, Saizen, and Zomacton. All of these are formulated as injections; growth hormone is not effective if administered in pill form because it is inactivated during digestion.
Injectable synthetic human growth hormone has been touted as an “anti-aging” remedy, but there is no reliable evidence for it serving that purpose. Using it as such is also illegal. Synthetic HGH is a prescription medication that has been approved by the U.S. Food and Drug Administration (FDA) only for specific uses.
In children, those uses include treating a diagnosed growth hormone deficiency or a condition that causes short stature. In adults, approved uses include treating a diagnosed growth hormone deficiency, short bowel syndrome, or muscle wasting caused by human immunodeficiency virus (HIV).
It is illegal for synthetic growth hormone to be prescribed for uses outside of those described by the FDA. An HGH prescription for growth hormone deficiency requires more than just a suspicion of low levels of growth hormone. Multiple tests must be conducted and reviewed by a doctor to confirm the presence of a growth hormone deficiency.
HGH Use Among Athletes
While HGH is intended as a prescription medication for people who have a growth hormone deficiency, it has gained notoriety as a banned substance in major sports. HGH is a banned substance according to the World Anti-Doping Agency (WADA), the National Collegiate Athletic Association (NCAA), the International Olympic Committee (IOC), and virtually all major professional sports leagues.
The role of HGH in doping by athletes began with the availability of recombinant HGH in the late 1980s. Use of HGH by athletes continued to rise and became the “drug du jour” in many sports. Anecdotal stories from athletes alleged that HGH injections could have an anabolic — meaning growing or building — effect on muscle mass while reducing fat and improving overall body composition. This increased the appeal of HGH to bodybuilders and athletes in a wide range of sports.
In addition to these alleged benefits, some athletes were willing to cheat with HGH because these injections were for many years difficult to detect. HGH is naturally produced by the body and its levels in the body can vary significantly from person to person and for any given individual based on mediating factors like stress, nutrition, age, and exercise. As a result, identifying doping with HGH was not cut-and-dried.
That changed with the 2004 and 2006 Olympic Games when new tests were validated that could distinguish between naturally-produced (endogenous) and synthetic HGH. Based on the ratio of types of HGH in the bloodstream, officials can reliably determine if an athlete has used synthetic HGH injections.
On top of being banned, HGH lacks clear evidence for its benefits as a performance-enhancing drug. While some research has found that it can boost muscle mass, there is doubt about how well that actually translates to improved athletic performance. In one small study, users of HGH reported higher fatigue and fluid retention without any gains in terms of athletic performance.
Furthermore, synthetic HGH injections can cause side effects. When used excessively, HGH can cause acromegaly and associated symptoms of swollen extremities, excess sweating, and joint pain. Doping with HGH may also come with risks of causing diabetes, high blood pressure, osteoporosis, impotence, and cardiovascular damage. Because it is only available through the black market, users are also in danger of using impure substances or cross-contaminated needles.
HGH Use as Treatment for Growth Hormone Deficiencies
Synthetic growth hormone is illegal for use by athletes seeking to enhance their performance, but it does have legitimate medical uses. Its primary indication is for treating growth hormone deficiencies in both children and adults.
In children, slowed growth is typically the first and main symptom of growth hormone deficiency. Growth charts plot a child’s height relative to their age, and a slow or flat rate of growth may indicate a growth hormone deficiency. Other symptoms can include a chubbier body, a younger-looking face, reduced muscle growth, low blood glucose levels, and a very small penis.
Growth hormone deficiency is often present at birth and identified before the age of 3. In most cases, the cause in unknown, but it can be present at birth or related to another condition such as a brain tumor, brain injury, or radiation therapy. Multiple tests may be needed to diagnose a growth hormone deficiency including imaging tests to examine the bones and a GH stimulation test that monitors whether the body is producing expected levels of growth hormone.
Daily injections of synthetic growth hormone can be used as a treatment for GH deficiency. The course of treatment may last several months with regular check-ins to monitor how a child is responding to the injections. The effect of the injections tends to be greater when administered at an earlier age, so it is advantageous to identify the condition as soon as possible.
Adults can also have a growth hormone deficiency. In some cases, this derives from a deficiency that began in childhood. In other cases, the deficiency begins in adulthood. This can happen as a result of harm to the pituitary gland or hypothalamus from a head injury, brain surgery, a tumor, or radiation therapy.
Symptoms in adults can include decreased muscle mass, weaker bones, fatigue, abdominal fat buildup, thinning skin, sleep disturbances, and mood problems. Definitive diagnosis of a growth hormone deficiency in adults requires at a minimum a blood test (if there is already established damage to the pituitary) and in many cases, GH stimulation testing, insulin tolerance testing, and/or a growth hormone–releasing hormone (GHRH) plus-arginine test.
Adult patients with an established GH deficiency may be prescribed treatment with daily synthetic hormone injections for an extended period that may last years. Treatment can help resolve symptoms of GH deficiency including improving sleep quality. However, not all adults with a deficiency receive treatment, especially people who have contraindications to injections such as diabetes or cancer. Patients receiving GH injections are typically closely monitored for potential side effects or interactions with other medications.
How to Increase Human Growth Hormone Naturally
Given the importance of growth hormone to our overall well-being, it is common to want to know how to naturally increase its production. Production and release of HGH is part of a complex biological system that incorporates feedback signals from the brain and body. As a result, it can be difficult to isolate specific actions that boost net levels of daily growth hormone production.
In healthy adults, growth hormone is produced in a controlled and regular fashion. Many of the habits that otherwise contribute to overall health, such as those listed below, can similarly help in naturally increasing production of HGH.
- Get quality sleep every night: we previously discussed the importance of sleep, especially deep sleep, in the regular production of growth hormone. Getting adequate sleep on a consistent schedule, which facilitates naturally moving through the sleep stages, can thus promote this significant nightly release of growth hormone.
- Eat a balanced diet: a person’s nutritional status plays into the production of growth hormone. Some research has indicated that excess caloric intake may suppress growth hormone production. Other studies have looked at various micronutrients and macronutrients to better understand their connection to GH production, but further research is necessary to be able to recommend a specific diet. For that reason, a diet that is well-balanced and includes necessary vitamins and minerals is likely to deliver the best outcomes.
- Exercise regularly: vigorous exercise can promote the production of growth hormone. There is evidence suggesting that this benefit can come from both aerobic training and resistance training. Independent of growth hormone production, regular exercise can deliver a slate of benefits for all aspects of health.
- Avoid smoking: the harms of smoking are well-established with regard to impacts on the lungs, heart, and other organs. While smoking increases short-term production of growth hormone, studies indicate that continued smoking can reduce overall GH production over time.
As these steps demonstrate, making healthy lifestyle choices is likely to have positive effects for overall health and for your natural production of growth hormone.