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Want to burn fat, build muscle, and protect your brain from decline? A groundbreaking new study shows exactly why skimping on sleep ruins your metabolism and focus.
A new study found the deep sleep circuit that builds muscle and burns fat may also be responsible for boosting your brain health.
Scientists at the University of California, Berkeley identified the brain circuit that explains why deep sleep is so essential for healthy brain function. The circuitry links sleep with the release of growth hormones. That connection explains why poor sleep can interfere with growth, muscle repair, fat metabolism, and brain function.
The discovery, which was published in the peer-reviewed journal Cell, suggests that the development of new therapies for sleep disorders and diseases related to metabolism and the brain, like Alzheimer’s or Parkinson’s, may be on the horizon.
Past studies had established that growth hormone levels rise during sleep, especially during the non-REM stage. In this study, scientists wanted to understand exactly how the brain controls this process.
Previously, blood tests were the only method to test growth hormone levels. But in this analysis, the researchers directly recorded neural activity in mice to see what happened during deep sleep.
Growth hormone is not only responsible for physical growth—but also glucose and fat metabolism regulation. If those two are consistently impaired, it can increase the risk of obesity, diabetes, and cardiovascular conditions.
How the growth hormone changes during sleep
The nerve cells responsible for growth hormone release are located in the hypothalamus, the brain region responsible for maintaining homeostasis.
Once the hormone is released, it activates a region in the brain stem that is involved in alertness, attention, and thinking. Problems within this region, the locus coeruleus, have been linked with numerous psychiatric and neurological disorders.
“Understanding the neural circuit for growth hormone release could eventually point toward new hormonal therapies to improve sleep quality or restore normal growth hormone balance,” Daniel Silverman, a UC Berkeley postdoctoral fellow and co-author of the study told Science Daily. “There are some experimental gene therapies where you target a specific cell type. This circuit could be a novel handle to try to dial back the excitability of the locus coeruleus, which hasn’t been talked about before.”
The researchers looked at the brain circuits of mice by placing electrodes in their brains and then stimulating the neurons in the hypothalamic region with light. Since mice naturally sleep in short bursts throughout the day, the pattern allowed the scientists to repeatedly observe the changes in growth hormone levels across sleep and wake cycles.
They discovered that the two peptide hormones responsible for regulating the release of growth hormone behave differently depending on the stage of sleep. While one peptide—GHRH—promotes growth hormone release, the other—somatostatin—suppresses it.
During REM sleep, both peptides increase, which leads to more growth hormone release. However, during non-REM sleep, somatostatin falls as GHRH rises, creating a different balance.
Additionally, the researchers found a new feedback loop in the brain stem region. As the growth hormone increases during sleep, it stimulates that region and promotes wakefulness. But when the activity grows too high, it starts to promote sleepiness instead.
“This suggests that sleep and growth hormone form a tightly balanced system: Too little sleep reduces growth hormone release, and too much growth hormone can in turn push the brain toward wakefulness,” Silverman said.
This newly identified system may also impact attention and other aspects of cognitive function as they are located in the same brain region.
Implications
Disruptions to the growth hormone often occur with insufficient sleep.
“Insufficient sleep has multiple detrimental effects, so everyone should take good sleep seriously,” Yang Dan, PhD, professor of neurobiology and vision science department at UC Berkeley told Inc. “For those who have trouble sleeping, they should seek medical attention.”
Dan added that disrupted hormone release caused by poor sleep not only impacts brain function but also the body’s metabolism, “causing reduced lean body mass, increased visceral fat, insulin resistance, etc.”
Dan added that the team hopes “these findings will eventually benefit human health.”
This post originally appeared at inc.com.
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