I’ve started a new habit. I’m going to bed earlier (9 is my goal) and waking up in the 5-6am window with a list of items I’m committed to accomplishing before I eat breakfast: a hydrocircuit (alternating between my hot and cold plunges), reading scripture or something older than me, prayer, a workout, and the sauna, in that order. So far, I feel amazing. But more than many things, I feel like I’m more productive and thinking more clearly, as if I have an easier time processing a lot of information at once.

In my opinion, I suspect most of us treat brain health like a shopping question. Which pill, which powder, which mushroom coffee. But in reality, the research points somewhere less exciting and far more useful: when you get light, when you move, what you eat, when you interact with people, and when you go dark.

The 2024 Lancet Commission on dementia estimated that dealing with 14 modifiable risk factors could prevent or delay as much as 45% of dementia cases. That number assumes every one of those factors is causal and fully removable, so treat it as a ceiling. Still, look at the list: physical inactivity, infrequent social contact, high blood pressure, hearing loss, high LDL cholesterol. Not one of them is sold in a bottle or as a subscription.

So here is what that could look like in your day.

Your brain keeps time with light. When I say brain I mean all the processes and chemical pathways and production systems in your body. When researchers put light sensors on the wrists of 86,772 adults in the UK Biobank, the people who got more daytime light had lower odds of depression, and the people who got more light at night had higher odds of depression, anxiety and several other psychiatric conditions. The pattern held after adjusting for physical activity, sleep quality and other health factors.

It was a snapshot study, so it can't prove the light caused the difference. But the direction lines up with everything we know about the body clock, and the fix costs nothing. Even a cloudy sky is many times brighter than most indoor rooms.

This is hard for me when I wake up a few hours before the sun, so I’m trying to get into bright light as quickly as possible to shut down melatonin production and align my body clock for the day.

This is the habit with the strongest evidence of anything in this newsletter.

In a randomized trial of 120 older adults, a year of brisk walking grew the hippocampus, the brain's memory center, by about 2%. That effectively reversed one to two years of age-related shrinkage, and memory improved with it. The group that only stretched kept losing volume.

You don't need a marathon. Among 78,430 adults wearing step trackers, about 9,800 steps a day went with roughly half the risk of developing dementia over seven years. Even 3,800 steps a day went with a 25% lower risk. That's an observational study, but it fits the trial above.

Where you walk matters too. In a University of Michigan experiment, people's directed attention improved more after a walk through nature than after a walk through city streets. A park beats a parking lot, every time.

This is where the most money gets spent on the least evidence.

The MIND diet was built specifically for brain health, and in observational studies it looked great. Then it was finally tested properly. In a three-year randomized trial of 604 people published in the New England Journal of Medicine, the MIND group and a control group on a mildly calorie-reduced diet both improved, and the difference between them was not significant. Brain scans didn't differ either.

What does show up is the other side of the plate. Among 10,775 Brazilian adults followed for eight years, those who ate more ultra-processed food than the lowest quarter of the group had a 28% faster rate of cognitive decline.

So the order of operations is simple. Before you buy anything labeled "brain food," stop eating the things that come in crinkly bags or plastic containers. Our house eats plant-forward and whole-food, and that, not any single ingredient, is the part I'd defend.

You've probably seen "dopamine fasting": a day with no phone, no music, no food you enjoy, to "reset" your brain. The premise is wrong. As a Harvard Medical School physician explains, dopamine doesn't run out, and avoiding pleasure doesn't refill a tank.

What dopamine actually does is more interesting. A study in Science found that dopamine changes how willing we are to spend mental effort, by shifting how the brain weighs the benefit of hard thinking against its cost. It's a motivation signal, not a pleasure chemical you can overdose on.

The useful question is what you spend your effort on. In a month-long randomized trial, researchers blocked mobile internet on people's phones for two weeks while leaving calls and texts alone.

Sustained attention, mental health and well-being all improved, and 91% of participants got better on at least one of those. When the scrolling went away, people spent more time with other people, exercising and outside.

That's the real "reset." Not fewer rewards, but different ones.

Loneliness may be the most underrated brain risk on the list. A meta-analysis of more than 600,000 people found loneliness went with a 31% higher risk of dementia, and the link held even after accounting for depression and social isolation.

It also connects back to sleep. As I wrote in last week's issue, one bad night makes people pull away from others. Poor sleep and loneliness feed each other, and both feed cognitive decline.

The fix is unglamorous: a recurring meal with people who know you, on the calendar, protected like a meeting.

Room light in the evening does more than we think. In a Harvard sleep lab study, ordinary room lighting before bed delayed the release of melatonin in 99% of people and cut the length of their melatonin night by about 90 minutes. Dimming the house after dinner is one of the cheapest upgrades there is.

Timing matters as much as duration. In a UK Biobank study of nearly 90,000 adults wearing sleep trackers, people who fell asleep between 10 and 11 p.m. had the lowest rate of heart disease, with risk climbing for both earlier and later bedtimes. What's good for blood vessels tends to be good for the brain.

As for how long, an analysis of UK Biobank participants landed on about seven hours as the sweet spot for cognition and mental health. Too little and too much were both tied to cognitive decline over time.

You may have heard that sleep "washes" the brain. A 2013 mouse study found the space between brain cells grew about 60% during sleep, speeding the clearance of amyloid, the protein linked to Alzheimer's. But a 2024 study from Imperial College London found the opposite: clearance in mice dropped during sleep. The cleaning mechanism is genuinely unsettled. What isn't in dispute is that short, irregular sleep tracks with a worse-working brain.

We sleep with a window open for the cool air. And if you have access to a sauna, a 20-year Finnish study of 2,315 men found that those who used one four to seven times a week had about a 66% lower risk of dementia than those who went once a week.

Keep your brain's schedule, and it will keep up with you.

-Jared

P.S. - My wife Baddie Crocker has a beautiful newsletter where she shares her perspectives on tending the land, recipes, women’s health and more.

P.S. - This newsletter does not provide medical advice. The content, such as graphics, images, text, and all other materials, are provided for reference and educational purposes only. The content is not meant to be complete or exhaustive or to be applicable to any specific individual’s medical condition.

Here are links to things that have helped me improve my health:

Whoop - Track your HRV and REM Sleep

Function Health - Optimize Your Health via 160+ BioMarkers

Here are a few topics I think you’ll love if you haven’t checked them out before:

How to Breathe for Better Health

How to Supercharge Your Sleep

The Power of the Sauna