Ten minutes of morning sun. I went looking for the study.

For years I’ve told people the same thing. Get outside in the morning. Move. Catch some daylight.

It’s one of the few things I can suggest with hardly any risk. I never actually looked into it. It sounded reasonable, seemed safe, and came from a Stanford professor whose podcast I had followed for years.

His book, Protocols, was released on September 15. I pre-ordered it in April last year, as soon as the release date was announced. On his podcast, he described it as his life’s work, putting everything he had learned about the human body into one book.

When my copy arrived, I started reading right away. After about 20 pages, I paused and realized I should have asked myself an important question much earlier.

The book gives a specific dose for morning light: five to ten minutes on a clear day, fifteen if it’s cloudy, and thirty if it’s heavily overcast, all within the first hour after waking. I had shared some version of these numbers for years. Some of my advice came straight from his podcast. I just assumed every number was backed by a study.

I never questioned where those numbers actually came from.

So I decided to find out.

Where I’m coming from

Andrew Huberman has done something unusual for a scientist: he brought lab science into everyday life. In my circle, people often quote his episodes, and many have started paying more attention to their sleep, light, and exercise because of him. He’s been at this for years. I’m newer to this conversation, and I’m not offering new science. What I can add is a doctor’s perspective and a busy person’s perspective. The seven habits I share at the end of this piece all come from his book’s protocols. Most of my questions were about the numbers.

A book for the public needs to keep things simple. I do the same in this newsletter. If I qualified every sentence like a research paper, no one would keep reading.

“Get daylight in the morning” is a broad stroke. “5 to 10 minutes, 15 if it’s cloudy” is a dose. A dose sounds more precise, like someone tested it.

We all run on n=1, me included. I wanted to find out which parts of the book are backed by research, and which are just one person’s routine.

Twenty pages became a month

The book includes 47 protocols. Its notes list 1,126 numbered entries and about 1,730 references, with some repeats. Tracking all of that by hand would take a team months, so I used AI.

The AI matched each reference to its protocol, found 1,243 different papers in PubMed (the main medical research database), and I pulled 438 Huberman Lab podcast transcripts. Then I reviewed all 47 protocols myself, one by one, and confirmed each result. Because the searches were focused, I call this a physician’s audit, with plenty of tech help.

PubMed marks 109 of those 1,243 papers as randomized trials, which is about one in eleven. At least 99 were animal studies. These tags might miss some studies, so consider these numbers as minimums. This count just describes the references; it doesn’t judge each claim.

Out of the 47 protocols, 22 give a specific number of minutes, grams, or degrees that I couldn’t find any study to support.

Next, I added up the time. For each protocol, I estimated how many minutes it would take per week if you followed it exactly. The total came to 32 hours a week.

That number isn’t entirely fair to the book. Some actions are counted twice, one is a writing exercise you do only once, and another applies only after a loss. Even after removing those, you’d still need 25 hours a week, or about three and a half hours a day.

No one is expected to do all 47 protocols. You still have to choose what works for you. My sorting has 13 to keep, 18 worth trying, 7 that depend on your situation, and 9 I’d skip.

Where the minutes came from

The research behind morning light is real. In the UK Biobank, more than 400,000 adults reported how long they spent outdoors in daylight. Each extra hour went with lower odds of depression and fewer insomnia symptoms [1]. In 88,905 people who wore a light sensor for a week, those with the brightest days had lower mortality over the next 8 years. Those with the brightest nights had higher mortality [2].

Both studies are observational, so they can’t prove cause and effect. People who spend more time outside are often healthier for other reasons. Both studies measured light exposure over the whole day.

What I couldn’t find was any study testing those exact minutes. No research compared 5, 15, and 30 minutes based on cloud cover, or looked at the first hour after waking.

The claim about cortisol was even less solid. The book says morning sunlight can raise your cortisol peak by up to 50%. The first study it cites for this is a lab experiment with eight men who stayed awake all night, then sat under bright lab lights for three hours starting at 5 a.m. [3]. That’s a real result, but it’s very different from spending ten minutes on your balcony.

A reader texted me this week: “9 months out of the year, I get up in darkness. How important is this?”

It’s less important than the stopwatch suggests. And I know the problem too well.

Berlin has its qualities, but its winters aren’t one of them. In December, it’s dark from around 4 pm until 8 am, and the sky is mostly gray in between. You can go weeks without seeing blue sky. It hits my mood hard.

So we set up a 10,000 lux daylight lamp on our breakfast table. I work in front of it each morning. I’ve never measured my cortisol, but I feel it helps me get through the Berlin winter. The book also recommends a lamp for dark winters, and I agree.

The evidence is real, but only for a specific group. In people diagnosed with winter depression, light boxes worked better than placebo across 19 small randomized trials [4]. I don’t have that diagnosis. I just have Berlin.

The doctor’s take: keep the habit, but don’t worry about the exact timing. Try to get outside in daylight most days, and in the morning if it works for you. The research supports bright days and dark nights. The specific minutes are just someone’s best guess. If you have bipolar disorder or an eye condition, check with your doctor before using a light box.

Where my advice differs

Coffee first, and here the book and the data mostly agree. The book says to avoid caffeine in the 8 to 10 hours before bed. A meta-analysis of 24 studies found that caffeine cut sleep by 45 minutes, pooled across the doses tested. It estimated that a regular coffee should come at least 8.8 hours before bed [5]. With an 11 pm bedtime, that’s about 2 pm.

Where I’d differ is in the morning. If you tend to crash in the afternoon, the book suggests waiting 30 to 90 minutes after waking before your first cup. I couldn’t find any human trials on that delay. If you enjoy coffee right when you wake up, go ahead and have it.

Next is alcohol. The book says not to drink any alcohol in the eight hours before sleep. If you go to bed at 11 pm, that means your last drink would be at 3 pm. Most people don’t live that way.

I’d put it simply: no amount of alcohol has been shown to help you live longer. In 107 studies with more than 4.8 million people, drinking up to 24 grams a day (about two drinks) didn’t lower mortality compared to never drinking. At 45 grams a day, the risk was 19% higher; at 65 grams, 35% higher. For women, the risk started at even lower amounts [6].

Even one drink a day is linked to a higher cancer risk. The risk of one type of esophageal cancer goes up by 30%, mouth and throat cancer by 17%, and breast cancer in women by 5% [7]. These are relative increases, and the absolute risks remain small. Drinking also affects sleep: from about two drinks, REM sleep decreases [8].

Now for strength training. The protocol recommends three sessions a week, about an hour each. But a meta-analysis of cohort studies found the lowest mortality risk with just 30 to 60 minutes of strength training per week. More than that, the effect is unclear [9]. Two whole-body sessions of 20 to 30 minutes each are enough.

Personally, I do more than that.

My n of 1

I train six to seven hours a week. Almost every morning I’m up between 5:30 and 6 and in the gym for an hour.

That’s at least six times more than what the mortality data suggests. I started wrestling at six, made the youth national team, and won a national title. For as long as I can remember, training has helped me relax and start my day right. My hour in the gym is the one constant in my week, and it isn’t going anywhere.

It’s not easy. We have three kids, and our mornings are often hectic. My wife and I still debate whether to spend that hour helping everyone get ready. We haven’t settled it yet.

None of this is scientific evidence, but my n=1. I’d stand by it at my kitchen table, but I wouldn’t put it on a prescription pad.

My doctor’s take: many of the doses in the book seem like personal routines. I couldn’t find studies to support them. That’s fine as a personal rule, but it becomes a problem when it’s presented as advice for everyone.

Most health research looks at the average person, but no one is truly average. We all differ in how we sleep, what foods suit us, how warm we like our bedroom, and when we train best. The list goes on. Use studies as a starting point, then see what works for you. If something feels good and helps you, it might be right for you. If it makes you feel worse, stop, no matter what the protocol says.

One note from me as a doctor: feeling good and being safe aren’t always the same. A nightcap can feel good, and so can a tan. The basics are clear: don’t smoke, don’t get sunburned, and go easy on alcohol. Beyond that, listen to your body. Doing more is fine if you enjoy it. Just be clear about what’s backed by data and what’s your own choice.

Where low-risk stops

Most of the 47 protocols are low risk. A few aren’t, and that’s where my view as a doctor comes in.

When I say “try it,” people hear it as advice from a doctor. If something goes wrong, they’ll say the doctor told them to do it. That’s why I consider the risks first. In two cases, the risks outweigh the benefits.

Warming the bed before you wake. The book says to warm the bedroom in the last one to two hours before waking, and links a warmer body to more REM sleep. A review of temperature and sleep found that with normal bedding, heat increases time awake and reduces REM [10]. I found no test showing that warming up late adds REM. It also requires a heating timer or an expensive mattress cover. Keep the bedroom cool all night.

Sun on bare skin. The book recommends 20 to 30 minutes of sun on bare skin at least three times a week. It also says sunburn is bad and that you should cover up when the UV index is high. My question was about the reason it gives: that the data showed higher testosterone linked to sun exposure in men and women. I read the study. Most of the paper is in mice. The 19 volunteers who went into the sun had their hormone activity inferred from blood proteins. The measured testosterone came from health records of young men, compared across the seasons. No woman’s testosterone was measured [11].

Without a burn, UV is still UV. The WHO’s cancer agency classifies solar radiation as carcinogenic to humans, its strongest level of evidence [12]. Be outside every day. Cover your face and scalp. From a UV index of 3, I use SPF 50.

The rest of my cut list would take more space than I have today. I’ll share more about the full audit in the coming weeks.

Try this today

Back to those 25 hours. Here’s what made the cut. Most of these habits don’t take extra time. The training adds about two hours a week. In my Upward ARC framework, almost all of this falls under Activate: sleep, movement, and food.

• Fix your wake time. Keep it the same time seven days a week, with at least 7 hours in bed. If you can only do one thing, fix the wake time first, then the bedtime. In 60,977 people, the more regular sleepers had 20 to 48% lower mortality than the least regular fifth [13]. That’s an association.

• Have your last coffee about nine hours before bed. Enjoy your morning coffee whenever you want.

• Skip the nightcap. If you drink, have no more than two drinks, have them early in the evening, and not every night.

• Aim for about 7,000 steps a day. Compared to 2,000 steps, this was linked to a 47% lower risk of death in a meta-analysis of cohort studies [14]. Try taking calls while walking.

• Do strength training twice a week for 20 to 30 minutes each session. Focus on whole-body movements: push, pull, squat, hinge, and carry.

• Do cardio twice a week for about 75 minutes total, including one higher-intensity session. Brisk walking counts toward the WHO’s 150 minutes of moderate activity per week [15]. If you’re inactive, have heart, metabolic, or kidney disease, or get symptoms when you exercise, check with your doctor before doing intense sessions.

• Eat protein and plants, mostly unprocessed foods. Have protein at every main meal, vegetables at two meals, use olive oil as your main fat, and eat fish twice a week. Cut out sugary drinks, processed meats, and packaged snacks. One tip from my own routine, though not backed by a study: do your shopping and meal prep on the weekend.

The light I still recommend

I still encourage people to go outside in the morning. I just don’t mention the exact number of minutes anymore.

For the reader who wakes up in the dark nine months a year: when the sun rises, go for a walk. Research supports getting more daylight throughout the day. If winter affects your mood, try using a lamp at the breakfast table. That’s what works for me, but your experience may be different.

Is there a health rule you follow but have never actually checked? Reply and let me know. I read every message.

Stay healthy.

Andre

PS: If you know someone who follows a morning routine or protocol, please forward this to them. That’s how this newsletter grows, and it’s the only way I want it to.

PPS: If a friend sent you this, you can sign up for Under Load, my Sunday edition, at andreheeg.com.

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References

[1] Burns, A. C., Saxena, R., Vetter, C., Phillips, A. J. K., Lane, J. M., & Cain, S. W. (2021). Time spent in outdoor light is associated with mood, sleep, and circadian rhythm-related outcomes: A cross-sectional and longitudinal study in over 400,000 UK Biobank participants. Journal of Affective Disorders, 295, 347–352. https://doi.org/10.1016/j.jad.2021.08.056

[2] Windred, D. P., Burns, A. C., Lane, J. M., Olivier, P., Rutter, M. K., Saxena, R., Phillips, A. J. K., & Cain, S. W. (2024). Brighter nights and darker days predict higher mortality risk: A prospective analysis of personal light exposure in >88,000 individuals. Proceedings of the National Academy of Sciences, 121(43), e2405924121. https://doi.org/10.1073/pnas.2405924121

[3] Leproult, R., Colecchia, E. F., L’Hermite-Balériaux, M., & Van Cauter, E. (2001). Transition from dim to bright light in the morning induces an immediate elevation of cortisol levels. Journal of Clinical Endocrinology & Metabolism, 86(1), 151–157. https://doi.org/10.1210/jcem.86.1.7102

[4] Pjrek, E., Friedrich, M.-E., Cambioli, L., Dold, M., Jäger, F., Komorowski, A., Lanzenberger, R., Kasper, S., & Winkler, D. (2020). The efficacy of light therapy in the treatment of seasonal affective disorder: A meta-analysis of randomized controlled trials. Psychotherapy and Psychosomatics, 89(1), 17–24. https://doi.org/10.1159/000502891

[5] Gardiner, C., Weakley, J., Burke, L. M., Roach, G. D., Sargent, C., Maniar, N., Townshend, A., & Halson, S. L. (2023). The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Medicine Reviews, 69, 101764. https://doi.org/10.1016/j.smrv.2023.101764

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[9] Momma, H., Kawakami, R., Honda, T., & Sawada, S. S. (2022). Muscle-strengthening activities are associated with lower risk and mortality in major non-communicable diseases: A systematic review and meta-analysis of cohort studies. British Journal of Sports Medicine, 56(13), 755–763. https://doi.org/10.1136/bjsports-2021-105061

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