Morning Sun: What Huberman gets Wrong
I spend 6-8 hours outside every day. Here's why.
“View morning sunlight to set your circadian rhythm” has become common health advice, popularized by influencers like Andrew Huberman and Bryan Johnson. They’re wrong. It misses how our circadian clocks actually work.
Circadian rhythm is not just about viewing morning sunlight. Our body clock doesn’t start in the morning and keep running smoothly on its own. It needs cues and signals throughout the day.
I spend 6 to 8 hours outside every day. Morning sun is 2 hours of that. The rest of the day matters just as much.
Why does circadian rhythm alignment matter?
Circadian rhythm is not just your body’s internal clock to keep time. It’s what powers the timing of your hormones, metabolism, immune system, gut cells, and every cell in your body. If there is disruption to your circadian alignment, the coordination between cells and hormones breaks down. It results in different cells working per their own timing without coordinating with each other. Your body begins to function like a discordant orchestra - cells don’t work in harmony with each other and create a noisy machine. Brain fog, trouble falling asleep, poor digestion could all result from circadian misalignment. It’s not just about giving your body the right signals, it’s about the right signals at the right time.
There’s a reason night shift workers have higher rates of breast cancer, type 2 diabetes, cardiovascular disease, and metabolic syndrome. It’s because their circadian timings are out of tune with how we evolved.
Circadian rhythm beyond morning sunlight
Viewing morning sunlight is sub-optimal advice on its own. Circadian rhythm alignment is about viewing the sunrise, getting ample afternoon sunlight, not using the wrong artificial lights at night, not eating out of sync with daylight, exposing your skin and eyes to sunlight, hydrating well, having good melatonin production, and going to bed by the right time.
Here is the full protocol I follow, sunrise to sleep. Skipping any of it disrupts your circadian rhythm.
Sunlight activates your master clock. We have a master circadian clock in the brain called the Suprachiasmatic Nucleus (SCN). Its activation is the most potent signal that the day has started. And it is activated by light, more specifically by full-spectrum sunlight. If your SCN does not get its sunlight cue, your body doesn’t fully know the day has begun. It will function sluggishly the rest of the day. Missing the morning sun is like driving a car with a broken engine. It’ll chug along but very sub optimally.
Go outside immediately upon waking and face east. No sunglasses, prescription glasses, contacts, sunscreen. The eyes are the gateway to the SCN. Spend at least 20-30 minutes in the sun if you can. Even 2-5 minutes is helpful versus seeing the sun hours after waking. As soon as I get up, I jump out of bed to go to my backyard. I brush my teeth outside in the sun - easy hack.
Catch the actual sunrise when possible. This is how we evolved. Sunrise is dominated by red and near-infrared wavelengths, with very little UV. These wavelengths support mitochondrial function and prime your skin and eyes for the UVA and UVB that come later as the sun climbs. The sun's spectrum changes from sunrise to midday to sunset, and the body uses these shifts to keep time. By missing sunrise, you skip the first cue and start the day on the wrong foot.
Sunlight cannot be replaced by artificial light, even on a cloudy day. No intensity of morning sunlamp can replace the signal provided by the sun. Direct sunlight is roughly 100 to 1,000 times brighter than indoor lighting (around 100,000 lux outdoors versus 100-500 lux indoors). Even on an overcast day, outdoor light is around 1,000-10,000 lux, far more than any office. Beyond brightness, each wavelength in sunrise gives a unique signal to the SCN and body, allowing us to start our day the way we evolved to. If you cannot view the sunrise, view the morning sun as soon as you wake up.
Afternoon sun is not to be feared. There is too much fear around UV light. The experiments demonizing UV have been conducted in isolation (UV is only a small fraction of the full solar spectrum) and are highly flawed. Humans evolved with full-spectrum sunlight for the entire day. The "UV is bad" explanation does not account for skin type, latitude, and the numerous benefits of UV light. In fact, avoiding the sun kills more people than skin cancer. Your eyes and body expect afternoon sunlight to keep the clock going. No afternoon sunlight is like stopping the clock midway. UVB in the afternoon helps not just with vitamin D production, but also with nitric oxide release that lowers blood pressure, beta-endorphin production for mood and pain regulation, and cholesterol sulfate which keeps cell membranes healthy. None of this happens with a vitamin D pill.
I spend 6-8 hours outside everyday. In the afternoons, I'm in the shade. Most people can't do this, but there are easy ways to work afternoon sun into a normal indoor workday.
Sneak afternoon sun into your workday. Step out for a 10-15 minute walk. Again, no shades, eyeglasses, contact lenses, sunscreen. 10 minutes will not burn you. If you are afraid of getting sunburnt, then build up your capacity for afternoon sun gradually.
If you work at home, open your office windows. Glass blocks UV and infrared light, and distorts sunlight’s full-spectrum. It also prevents Co2 buildup, which creates brain fog.
Every time you take a break to go to the bathroom or get food, go out in the sun for 2-3 minutes. This too helps.
Don't skip breakfast - your gut has its own clock. Intermittent fasting has made it popular to skip breakfast. It’s not just our brain that has a master clock, but every cell and organ in the body has its own clock. When we skip breakfast, our gut clock thinks the day has not started yet. This creates a desynchrony between our brain clock and the other clocks, and shifts the timing of the gut clock to run behind. Smooth body functioning requires timing signals in the body to be aligned.
Eating after sunset confuses your body. For almost all of human history, before artificial light, we finished dinner by sunset. Eating post sunset creates a disconnect in our body clocks. Our brain senses that we should wind down, but our gut, liver, and kidney clocks (all involved in digestion) remain activated and so do different hormones and enzymes. This not only creates noise in the body, but also leads to poor digestion before bedtime.
Watch the sunset. Give your brain the cue that the day has ended, it’s time to start winding down.
Use red incandescent bulbs after sunset. Your blue-rich LEDs are wrecking your sleep. The ideal is no artificial light after sunset. The realistic version is red incandescents as they don’t disrupt sleep and melatonin. Our eyes are particularly sensitive to blue light, which suppresses melatonin production at night. Melatonin is not just a sleep hormone, it's a repair hormone. Disrupt melatonin and you disrupt your body's repair signals at night.
Strip blue light from your screens at night. Blue LEDs aren't just in your house lighting. They are hiding in your phone, computer, and TV screens too. If your house is red but your phone is blue, you are still signaling daytime to your brain. The same way I switched out the lights in my house, I have stripped blue light from every screen I use. The exact steps are laid out here - 60 seconds per device.
Expose your skin to sunlight, not just your eyes. Our eyes are not the only organ attuned to light signals. Our skin senses light too. Skin is the largest organ in our body, and exposing as much of it to sunlight as possible helps with proper circadian signaling.
Circadian rhythm alignment is not a single morning habit. It's a 24-hour conversation between your body and the environment. The sun, the dark, the food, the timing - they're all signals, and your cells are listening to all of them. Most of this is environment, not effort. Once you align your day with the sun, the rest takes care of itself.
Aastha
Browse my Health on Easy Mode setup across 15+ categories (non-toxic kitchen, clean water, skincare, diagnostics, lighting).
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