We’re Still Discovering What Sleep Does for Us, and the Latest Research Is Fascinating

By Wendy Francis, NBC-HWC – Board-Certified Health & Cognitive Coach

Just when we think we understand how important sleep is, scientists discover something else.

For years, we have known that sleep helps with memory, mood, immune function, metabolism, recovery, and brain health. But researchers are still learning exactly how some of these processes happen inside the brain.

A recent article published by ScienceDaily, based on research from the University of California, Berkeley and a study published in the journal Cell, highlights a fascinating discovery about the relationship between sleep, growth hormone, metabolism, muscle and bone health, and even wakefulness.

And I think the bigger message is this:

What Did the Researchers Discover?

Scientists have known for decades that growth hormone is closely connected to sleep. Growth hormone is not just important for growing children and teenagers. In adults, it also plays roles in maintaining muscle and bone and regulating metabolism.

What researchers have not fully understood is exactly how the brain controls growth hormone release during the different stages of sleep.

In this research, scientists studied brain activity in mice and mapped a circuit involving the hypothalamus, an area of the brain that helps regulate many essential functions, and the locus coeruleus, a brainstem region involved in alertness, attention, arousal, and cognitive function.

The researchers found a complex feedback system. Sleep influences the release of growth hormone, and growth hormone appears to feed information back into brain systems involved in wakefulness.

In other words, sleep and wakefulness are not simply an on-and-off switch. They appear to be part of a carefully regulated biological conversation.

Your Body Is Not “Shut Down” While You Sleep

I think this is one of the biggest misunderstandings about sleep.

We tend to think of sleep as doing nothing.

We say things like:

• “I’ll sleep when I’m dead.”
• “I can function on five hours.”
• “I’ll catch up this weekend.”
• “I just don’t have time for eight hours of sleep.”

But while you are sleeping, your body and brain are far from inactive.

Sleep is associated with memory processing, hormone regulation, metabolic function, immune activity, tissue recovery, and many other processes that researchers continue to study.

This latest research adds another piece to that puzzle by helping scientists better understand the brain circuitry connecting sleep and growth hormone release.

Why Does This Matter for Your Health?

Most people are looking for ways to improve their health by adding something.

A new supplement.
A new diet.
A new fitness tracker.
A new powder.
A new morning routine.

But sometimes improving our health starts by respecting the basic biological needs we already have.

Sleep is one of those needs.

If you exercise regularly but consistently cut your sleep short, you may not be giving your body the recovery environment it needs.

If you are working on improving your metabolism, nutrition is important, but sleep belongs in that conversation too.

If you are concerned about focus, memory, and cognitive health, we cannot talk only about brain games and supplements. We also have to talk about sleep.

This is exactly why I continue to teach a back-to-basics approach to health. The body is incredibly complex, but the foundations are still remarkably simple:

The Part I Find Most Fascinating: We Are Still Learning

Sometimes we talk about the human body as if we have everything figured out.

We don’t.

We know a tremendous amount about sleep compared with what we knew decades ago, but there is still much to learn about why we sleep, how different sleep stages interact with the rest of the body, and how sleep affects different people across the lifespan.

This research is a perfect example.

Scientists already knew there was a relationship between sleep and growth hormone. What they are now beginning to map more clearly are the specific brain circuits and feedback mechanisms involved in that relationship.

That distinction matters.

Science often moves forward one layer at a time. We may know that two things are connected long before we fully understand the exact mechanism connecting them.

And when it comes to sleep, I believe we are going to continue learning just how important it really is.

What We Know and What We’re Still Learning

What we know:

• Sleep is essential for physical and cognitive health.
• Growth hormone release is closely associated with sleep.
• Different stages of sleep serve different and overlapping biological functions.
• Consistently poor sleep is associated with numerous health risks.
• Sleep quality matters alongside nutrition, movement, stress management, and other lifestyle factors.

What we are still learning:

• The full complexity of the brain circuits that regulate sleep and wakefulness.
• How sleep-related hormone systems interact with cognition and metabolism.
• How findings from animal models translate into human health and potential treatments.
• How sleep needs and biological responses differ by age and individual circumstances.
• How researchers might eventually use these discoveries to better understand or treat sleep and metabolic disorders.

This particular study was conducted in mice, which is an important limitation. Animal research can help scientists identify biological mechanisms and guide future research, but we should not assume that every finding will work exactly the same way in humans.

What Can You Do Right Now?

You do not need to wait for the next scientific discovery to start respecting your sleep.

Start with the basics:

• Keep your sleep and wake times as consistent as possible.
• Give yourself enough time in bed to actually get the sleep your body needs.
• Get morning daylight to help support your circadian rhythm.
• Move your body during the day.
• Be mindful of caffeine later in the day.
• Create a short wind-down routine before bed.
• Reduce bright light and stimulating phone use as bedtime approaches.
• Keep your bedroom dark, quiet, and comfortably cool.

You do not have to create the perfect sleep routine overnight.

Pick one habit and start there.

Maybe tonight you go to bed 30 minutes earlier.

Maybe tomorrow morning you step outside for a few minutes of daylight instead of immediately reaching for your phone.

Maybe you move your afternoon coffee a little earlier.

Small changes, repeated consistently, can create meaningful improvements over time.

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Sources

ScienceDaily: “Scientists discover the deep sleep circuit that builds muscle, burns fat, and boosts the brain.” Based on materials provided by the University of California, Berkeley.

Cell: Ding, X., Hwang, F.J., Silverman, D., et al. “Neuroendocrine circuit for sleep-dependent growth hormone release.” Cell, 2025; 188(18): 4968–4979. DOI: 10.1016/j.cell.2025.05.039.

University of California, Berkeley: “Sleep strengthens muscle and bone by boosting growth hormone levels. UC Berkeley researchers discover how.” September 8, 2025.