healthy. Bodybuilders, for example, rely on deep sleep to boost levels of growth hormone, which builds muscle and burns fat.
Teenagers also need plenty of sleep to reach their full height. But scientists have long wondered why missing out on sleep—especially the deep, early part of the night called non-REM sleep—reduces the release of growth hormone.
Now, a team of researchers at the University of California, Berkeley, may have found the answer. In a new study published in the journal Cell, they explored how the brain controls growth hormone release during sleep and uncovered a new feedback system that keeps hormone levels in balance.
This discovery could one day lead to better treatments for people who have sleep problems linked to conditions like diabetes, obesity, or even brain diseases such as Parkinson’s and Alzheimer’s.
Lead author Xinlu Ding explained that while past research mostly measured growth hormone through blood samples, their team recorded brain activity directly in mice to see how growth hormone is controlled during sleep. By doing this, they mapped a key brain circuit that connects sleep and hormone release.
Growth hormone doesn’t just help with building the body—it also controls how the body uses sugars and fats. That means poor sleep, which lowers growth hormone levels, could raise the risk for health issues like diabetes, obesity, and heart disease.
The part of the brain responsible for releasing growth hormone is deep inside an area called the hypothalamus. This ancient part of the brain is found in all mammals. It contains special neurons that produce hormones to either promote or block the release of growth hormone: one is called GHRH, and the other is somatostatin.
Once growth hormone is released, it travels to another brain region called the locus coeruleus, which helps control wakefulness, attention, and mental alertness.
In this study, the researchers used light to stimulate specific neurons in mice and recorded how brain activity changed during sleep. Mice have short sleep cycles throughout the day and night, which gave the scientists many chances to observe growth hormone patterns.
They discovered that the two hormones, GHRH and somatostatin, behave differently depending on the sleep stage. During REM sleep, both hormones rise, which increases growth hormone. But during non-REM sleep—the deeper sleep stage—GHRH goes up slightly, while somatostatin drops. This also leads to more growth hormone release.
The team also found that growth hormone itself sends a message back to the brain’s wakefulness center, the locus coeruleus. At first, more growth hormone can make this brain area more active, which helps you wake up feeling refreshed.
But if it becomes too active, it can actually cause drowsiness. This surprising feedback loop shows that sleep and growth hormone are part of a delicate system that keeps the body and brain in sync.
Too little sleep lowers growth hormone. Too much growth hormone may trigger the brain to promote sleepiness. This push-and-pull system keeps our sleep, energy levels, and metabolism in a healthy balance.
Growth hormone may also improve thinking and focus when we’re awake. So it doesn’t just help build muscles—it may also help sharpen our minds. With this new understanding, researchers may one day develop better therapies for sleep and hormone disorders by targeting this brain circuit.
If you care about sleep, please read studies about How sleep affects type 2 diabetes management and findings of Connection between sleep apnea and high blood pressure you need to know.
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