REM Sleep Benefits: What a 95,000-Person Study Just Revealed

“Doctor, I’m in bed for eight hours, but I wake up feeling like I never slept.” I hear some version of that sentence in my practice almost every week. Usually the person saying it has done everything they were told: they go to bed on time, they stay in bed, and they count the hours. Yet their body is telling them something is missing.

A large new study suggests what that missing piece might be. Most of us measure sleep in hours, but researchers are now finding that the kind of sleep you get, and how steady your sleep schedule is, may matter just as much. The REM sleep benefits in particular caught my attention, because REM, or dream sleep, turned out to be linked with a lower risk of a remarkable number of health conditions.

According to the report on ScienceDaily, scientists followed more than 95,000 adults who wore wrist sensors for a full week, then tracked their health for nearly nine years. People who got more REM sleep had a lower risk of 83 different diseases. Let me walk you through what they found, what it does and does not prove, and the simple, natural habits I recommend to protect your sleep starting tonight.

🔬 What the 95,000-Person Sleep Study Found

The study was published in September 2026 in PLOS Medicine by Jingsong Luo, Rui Chen and their colleagues. They used the UK Biobank, a large health database of mostly middle-aged and older adults in the United Kingdom. The average participant was 56.2 years old, which makes this research especially relevant to many of my readers.

How the Researchers Measured Sleep

Each of the 95,559 participants wore a wrist accelerometer (a small motion sensor, similar to what is inside many fitness watches) for 7 consecutive days and nights. A deep-learning computer program then estimated their sleep stages from their wrist movements. The team followed everyone for a median of 8.9 years and checked their health records against more than 1,000 possible disease outcomes.

That last part is called a phenome-wide association analysis. In plain English, instead of asking “Is sleep linked to heart disease?” the researchers asked, “Which of more than a thousand conditions show up more or less often depending on how people sleep?”

The REM Sleep Findings

The headline result was about REM sleep. For every additional 47.6 minutes of REM sleep, participants had a lower risk of 83 diseases. Researchers express this with a “hazard ratio.” A hazard ratio of 1.0 means no difference in risk, and any number below 1.0 means lower risk.

For heart failure, the hazard ratio was 0.74. For dementia it was 0.54, and for Parkinson’s disease it was 0.20. Those are striking numbers. But remember, they describe a pattern seen across a large group of people, measured per 47.6 minutes of REM. They are not a promise of what will happen to any one person.

Deep Sleep, Duration and Irregular Schedules

The study looked at much more than REM. Here is what else the researchers reported:

• Deep sleep: More deep sleep was linked to lower risk of 7 conditions, including type 2 diabetes and major depressive disorder.
• Total sleep time: Sleep duration had a curved, or “non-linear,” relationship with 86 conditions. For 69 of them, risk was lowest in the 6 to 8 hour range.
• Short sleep: People sleeping under 5 hours a night had increased risk of 37 conditions.
• Irregular and broken sleep: More night-to-night irregularity and more time awake after first falling asleep were each linked to higher risk of several conditions, including anxiety and substance use disorders.

In all, the authors reported 156 significant links between sleep patterns and disease.

What This Study Cannot Tell Us

I always want to be honest with you about the science. This was an observational study, which means it found associations, not cause and effect. The authors themselves say it cannot establish that sleep patterns directly cause disease risk.

There is also something called reverse causation. Depression, for example, can disrupt sleep on its own, so poor sleep may sometimes be an early sign of a problem rather than its cause. The sleep stages were estimated by an algorithm from one week of wrist movement, not measured with EEG (the brain wave recordings used in sleep labs). And the UK Biobank group is mostly middle-aged and older adults in the UK. One study is never the final word, but this one is large, careful and worth taking seriously.

🧠 Deep Sleep vs REM Sleep: Understanding the REM Sleep Benefits

Your night of sleep is not one long, even stretch. Your brain moves through cycles of lighter sleep, deep sleep and REM sleep several times each night. Each stage seems to do different work, and that is part of why the quality of sleep matters, not only the quantity.

Deep sleep, also called slow-wave sleep, is the heaviest, hardest-to-wake stage. Your brain waves slow down and your body shifts into a restorative mode. This is the stage most people mean when they say they “slept like a rock.”

REM sleep stands for rapid eye movement sleep. It is the stage when most vivid dreaming happens and the brain becomes far more active, even as the body stays still. Scientists have long connected this stage with memory and emotional processing, which helps explain why researchers are so interested in its links to brain health.

When I explain this to patients, I compare it to a home that needs both a deep clean and careful organizing. Deep sleep and REM sleep each have their own job, and shortchanging either one leaves the house in less than its best shape. I have written before about how sleep loss affects brain health, and this new research adds another layer to that picture, especially for those of us thinking about sleep and dementia risk.

You can read more about that aging research in the ScienceDaily summary. Taken together, these two studies point in the same direction: our bodies seem to do best in a steady middle zone, not at the extremes.

⏰ How Much Sleep Do You Need? Finding the Sweet Spot

This is one of the most common questions I am asked, and the new study adds an interesting twist. For most of the conditions it looked at, risk was lowest among people sleeping roughly 6 to 8 hours. As Medical News Today points out, that is slightly different from the commonly quoted 7 to 9 hours.

Please do not take this as permission to aim for only 6 hours. Mayo Clinic recommends at least seven hours for healthy adults, and I agree. The way I would sum it up is this: roughly 6 to 8 hours, and consistent, with seven or more as a wise target for most adults.

The bigger warning sign in this research was very short sleep. Sleeping under 5 hours a night was linked to increased risk of 37 conditions. If you are running on that little sleep, your body is likely paying a price, even if you feel you have “gotten used to it.” If daytime fatigue is your constant companion, my article on why you may always feel tired is a helpful next read.

When to Talk With Your Doctor

Sometimes poor sleep is a habit problem, and sometimes it is a medical one. Please see your doctor if you notice any of the following:

• Loud snoring, or a spouse who notices you gasping or pausing your breathing at night
• Severe sleepiness during the day
• Ongoing trouble falling or staying asleep
• Changes in your memory
• Regularly sleeping 9 or more hours and still feeling unrested

These can signal sleep apnea or other problems that deserve a proper evaluation. If you take any medication and wonder whether it affects your sleep, talk with your doctor rather than changing anything on your own.

🌙 Simple Habits That Protect Deep Sleep and REM Sleep

Here is the encouraging news. You cannot simply order your brain to produce more REM sleep, and a wrist device cannot perfectly tell you how much you are getting. But you can create the conditions your body needs to move through its natural sleep cycles. God designed your body with a built-in rhythm, and most of these habits simply work with that design instead of against it.

Caffeine and Deep Sleep: The Hidden Connection

Many of my patients tell me, “Coffee doesn’t bother me. I can drink a cup at dinner and fall right asleep.” A recent review of EEG sleep studies, reported on ScienceDaily and published in the journal Nutrients, suggests that may not tell the whole story.

The reviewers found that caffeine may reduce slow-wave, or deep sleep, activity even when total sleep time looks normal. Sensitivity varies from person to person. For some people, even earlier-day caffeine may matter, so both how much you drink and how long your body has to clear it count. This was a review of existing research rather than a new trial, but it fits what I see in practice.

With that in mind, here are the habits I recommend, drawn from the experts quoted by Medical News Today and from the Mayo Clinic guidance:

Two more notes. Mayo Clinic Health System suggests avoiding long naps, which can steal from your nighttime sleep drive. And nicotine, like caffeine, takes hours to wear off. If your schedule has drifted over the summer or a busy season, my guide to a circadian reset for your body clock walks through how to gently bring it back in line, and the same principles apply any time of year.

When I wrote The Seven Pillars of Health, I placed sleep among the foundations of a healthy life, right alongside water, food, movement, detox, supplements and managing stress. This new research is a powerful reminder of why. Sleep is not a luxury we earn after everything else is done. It is one of the pillars everything else rests on.

✅ Your 7-Day Sleep Action Plan

You do not need to change everything at once. Try one or two of these each day this week and notice how you feel.

1. Pick your wake time. Choose a time you can keep seven days a week and set your alarm for it, weekends included.
2. Count backward to your bedtime. Aim for at least seven hours in bed asleep, and plan your evening around that target.
3. Greet the morning light. Spend a few minutes outside after waking, perhaps with your morning prayer or a short walk.
4. Move your last cup earlier. Finish caffeine by 3 pm, or earlier if you suspect you are sensitive.
5. Prepare your room. Make it cool, dark and quiet. Remove or cover any glowing lights.
6. Start a 60-minute wind-down. Turn off screens, dim the lights, enjoy a cup of herbal tea, read Scripture, and write down three things you are grateful for.
7. Release the day to God. Before you turn out the light, pray over whatever is weighing on you and leave it in His hands. If sleep problems persist, make an appointment with your doctor.

❓ Frequently Asked Questions

What are the main REM sleep benefits?

REM sleep is the dreaming stage of sleep, and scientists have long connected it with memory and emotional processing. In this new study of 95,559 adults, more REM sleep was associated with a lower risk of 83 diseases, including heart failure and dementia. Because the study was observational, it shows a link rather than proof that REM sleep causes lower risk.

How much sleep do you need after 40?

Mayo Clinic recommends at least seven hours a night for healthy adults. In this study, risk was lowest for most conditions in the 6 to 8 hour range, and sleeping under 5 hours was linked to increased risk of 37 conditions. Consistency matters too, so aim for a similar schedule every night.

What is the difference between deep sleep vs REM sleep?

Deep sleep, or slow-wave sleep, is the heaviest stage, when brain waves slow and the body shifts into a restorative mode. REM sleep is when most vivid dreams happen and the brain is much more active. You cycle through both several times a night, and the study linked each stage with different health outcomes.

Can caffeine affect deep sleep even if I fall asleep easily?

For some people, yes. A recent review of EEG sleep studies found that caffeine may reduce deep sleep activity even when total sleep time looks normal. Sensitivity varies, so finishing your last cup earlier in the day is a simple experiment worth trying.

Are sleep trackers accurate at measuring REM sleep?

Wrist devices estimate sleep stages from movement, so their numbers are approximations, not lab measurements. Even this study used an algorithm rather than EEG brain recordings. A tracker can help you notice patterns, but how you feel during the day and a conversation with your doctor matter more than any single number.

🙏 A Final Word

For years we have asked, “How many hours did you sleep?” This research invites a better question: “How well, and how steadily, did you rest?” It does not prove that more dream sleep will protect you from any particular disease. But it adds to a growing body of evidence that quality, consistent sleep is one of the true pillars of prevention.

The beautiful thing is that the habits that support good sleep are free and within reach of nearly everyone: a steady wake time, morning light, an earlier last cup of coffee, a cool dark room and a peaceful heart at bedtime. Start with one change tonight. Keep coming back to drcolbert.com for more research explained in plain language, and share this article with someone you love who could use better rest.

May the Lord give you sweet sleep and renewed strength each morning.

Dr. Don Colbert, MD