Many people know that a good night’s sleep helps the body grow and repair itself, but not everyone understands why.
Sleep, especially the early deep stage called non-REM sleep, plays a key role in releasing growth hormone. This hormone is essential for building strong muscles and bones, burning fat, and keeping the body healthy.
Teenagers in particular need enough sleep to reach their full height, because growth hormone is released most during the night. Bodybuilders also know how important it is, since growth hormone boosts muscle strength and recovery.
For decades, scientists have known that growth hormone is connected to sleep, but they did not know exactly how the brain controls this process.
A new study from the University of California, Berkeley, published in the journal Cell, has uncovered how the brain’s circuits regulate growth hormone release during sleep.
The researchers discovered a feedback system in the brain that carefully balances growth hormone levels, which may explain why poor sleep lowers hormone release.
This discovery is important because it links sleep and hormone regulation in a new way. It also opens possibilities for treating sleep disorders that affect metabolism, such as diabetes, as well as age-related conditions like Parkinson’s and Alzheimer’s disease.
Growth hormone does more than just build muscle and bone. It also plays a major role in controlling how the body uses sugar and fat. This means that poor sleep, which lowers growth hormone, can increase risks for obesity, diabetes, and heart disease.
The brain area involved in this process is the hypothalamus, a small but powerful region deep inside the brain that controls many vital functions in all mammals.
Inside the hypothalamus, two sets of neurons work together to release growth hormone. One group, called GHRH neurons, encourages hormone release. The other group, somatostatin neurons, works like a brake to slow it down.
The researchers studied this by recording the brain activity of mice, which sleep for short bursts throughout the day and night. This allowed them to monitor growth hormone changes during different phases of sleep.
They found that during REM sleep, both GHRH and somatostatin are active and together help release growth hormone. During non-REM sleep, the balance shifts, with less somatostatin and moderate GHRH activity, also leading to growth hormone release.
Once released, growth hormone influences another part of the brain called the locus coeruleus, which controls wakefulness, attention, and thinking. Interestingly, the study found that growth hormone and sleep form a balanced cycle. Sleep increases growth hormone, and growth hormone then feeds back to regulate wakefulness.
Too little sleep means less growth hormone, but too much growth hormone can push the brain toward wakefulness, showing a delicate balance. This cycle is vital not only for physical growth and repair but also for mental sharpness and overall health.
The researchers suggest that this new knowledge could lead to new types of therapies. For example, targeting this brain circuit could help people with sleep problems restore their hormone balance.
This may also improve metabolism and protect against diseases. In addition, since the locus coeruleus affects attention and memory, growth hormone might also play a role in keeping the brain sharp after waking.
In summary, this study shows how deeply connected sleep and growth hormone are. Sleep drives the release of growth hormone, and growth hormone in turn helps regulate wakefulness and supports body and brain health.
The findings highlight why getting enough sleep is so important for both young people who are still growing and adults who want to stay healthy.
The study is published in Cell.
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