How Does Sleep Help Our Muscles And Brains?

Most of us already know that getting enough sleep on the reg can reduce heart attack risk, make you more likely to exercise, and even help you live longer.

But working out exactly why that might be can prove difficult. In recent years, scientists have been looking more closely at the biological mechanisms behind sleep’s benefits.

And recently, a new paper published in the journal Cell identified a deep sleep circuit that might play a role in building muscle and improving our brain function.

The researchers discovered a feedback system that keeps certain hormones in check during sleep, too.

We’ve known for a long time that growth hormone, which is linked to stronger cartilage, muscle, and bone and an improved metabolism alongside a potentially lower heart disease and diabetes risk, is produced during sleep.

But we weren’t really sure how it was released.

In this paper, researchers looked at the brains of mice. They found that growth hormone-releasing hormone (GRGH) and somatostatin, which can suppress the hormone, both rise during rapid eye movement (REM) sleep. That leads to a greater overall release of growth hormone.

During other parts of sleep, though, somatostatin dips while GRGH only rises a little.

Additionally, the scientists found a feedback mechanism in a part of the brain called the locus coeruleus, part of the brain associated with attention, sleep-wake cycles, and thinking.

When growth hormone slowly builds up during sleep, it begins to wake us up bu stimulating this brain region, the study found. But when a more sudden influx of the hormone comes, it seems to make us sleepier.

“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,” study co-author Dr Daniel Silverman said.

“Sleep drives growth hormone release, and growth hormone feeds back to regulate wakefulness, and this balance is essential for growth, repair and metabolic health.”

The hormone’s interaction with our locus coeruleus, which keeps us attentive and alert, might also explain sleep’s cognitive benefits, he added.

“Growth hormone not only helps you build your muscle and bones and reduce your fat tissue, but may also have cognitive benefits, promoting your overall arousal level when you wake up.”

Researchers hope these findings can inform future therapies.

“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,” Dr Silverman stated.

“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.”