james’s posthaven

This is a series on how to improve sleep, focus, and learning. I summarize learnings from Dr. Huberman’s lectures. The relevant lectures for this post are episode two and episode three. The first episode is a good baseline for the rest of his lectures. I’m a big fan of his work because Dr. Huberman explains key mechanisms and provides behavioral tools we can safely experiment on our own without supplements or hacks.

The late morning sun beamed down as I sprawled out in the shallow edge of Tenaya Lake. Warm alpine waves lapped at my dirt-ridden body as day trippers peered over. I didn’t care. I felt renewed after a week of backpacking in Yosemite. This impromptu nature bath helped, too.

How does a vacation into the woods reset your mind and body? It’s a different type of feeling compared to a jet-setting vacation into a major city or a fist pumping beach resort. Those seem to result in vacation lag, where another vacation is required before making eye contact with real life.

Emerging from the woods after a camping trip, whether one night or seven, seems to provide a therapeutic “reset” type of effect. My sleep schedule is often corrected and the night owls joining my trips seem to be able to sleep and rise early with no problems. What gives? The Huberman Lab podcast connected a few dots.

Humans have an internal clock: the circadian rhythm. This rhythm is the ebb and flow of our sleep and wake cycles. The cycle is 24 hours, mapping appropriately to a human day.

How does this process know the start and end points? Sunlight!

Here’s how it works: we have neurons in the eyes called retinal ganglion cells and in those cells are melanopsin, which are sensitive to blue and yellow light. These neurons are not related to vision function as they are also active in the blind. Located in the bottom of our eyes, they are sensitive to overhead light (evolution is so clever, the sun is always overhead). Blue and yellow light is naturally available when the sun is low in the sky, during sunrise or sunset.

The low light during sunrise triggers the retinal ganglion cells to communicate with our suprachiasmatic nucleus. This dope sounding part of our brain, located behind the roof of our mouths, is responsible for setting our circadian rhythm. It does this by secreting peptides (basically proteins) which carry a signal to the rest of the body, telling our organs to wake the hell up! This is also how our body’s temperature is synchronized, but I’ll cover temperature in the next post. We’ll focus on the light trigger.

In the afternoon, the light around sunset (roughly an hour before), adjusts your retinal sensitivity to light, making you less likely to be triggered into wakefulness by incoming light after dark. Dr. Huberman calls this the Netflix inoculation, protecting you somewhat from night time exposure to digital devices. I suspect the feature is meant to reduce sensitivity against night-time sources of light*, such as fire or moonlight, allowing our ancestors to sleep soundly at night.

This process, starting with light available around sunrise, anchors our bodies’ hormonal rhythms to a starting point in the day.

It was a sturdy design for most of human history, perfect for nomadic hunter gatherers in the wild and before we invented screens and became an indoor species.

Today, windows and windshields dampen the effect of morning light arriving into our homes by 50%, suppressing the mechanism to wake up the body. Digital devices and our homes have become a source of artificial sunlight, available at the wrong hours. Extended exposure to device light late at night throws our body for a loop, suppressing melatonin, which is the hormone responsible for our sleep drive and delays our circadian rhythm, affecting memory, learning, and even linked to depression.

This is where an adventurous backpacking or camping trip comes in.

When camping in the woods, you’re mimicking a perfect day as far as your circadian rhythm goes. The moment the sun rises, you’re getting low solar angle light energy into your eyes before you wake. There are no windows or windshields dampening the effect of morning light. 

It’s not just sunrise. You’re outside and it’s likely you catch sunset as well. And since you’re in the backcountry, there’s very little Netflix or device fiddling after dinner. Just the vast open night sky, music of the woods, and lilting conversation with your companions. What a bummer.

Combine all of these factors and backpacking through the woods is exactly what our circadian rhythm was designed for. Even a study from the University of Colorado verified the positive impacts on circadian rhythm during a weekend of camping.

Dr. Huberman suspects a lot of night owls actually just have their circadian clocks shifted, which explains why the night owls on my backpacking trips normalize their schedules.

As much as I’d love to live in the backcountry, it’s not practical. Below is what Dr. Huberman suggests for setting the circadian rhythm properly for improved sleep and focus. These are all behavioral experiments you can run yourself. As far as I can tell, none of the suggestions look out of the ordinary.

What does an ideal day look like from a light perspective?

• Watch sunrise or get roughly 100,000 lumens before 9am. Dr. Huberman says not to stare directly at the sun, we should listen to him.
• Continue to get light throughout the day, from your screen, or outdoors, because you’re just a plant with more complicated feelings.
• Watch sunset or take a walk in the hour before sunset to adjust retinal sensitivity.
• In the hours before sleep and throughout (11pm to 4am being most critical), stay away from bright artificial overhead lights or devices. Floor lamps and candlelight are ideal for night time reading.

How can you tell you’re getting 100,000 lumens?

• Download one of the free light meter apps on your phone. It uses the camera to determine lumen availability around you. With this, you can get a sense of how many lumens are available in different weather conditions and time of year. You can even experiment with what windows and windshields do to lumen strength (roughly 50% reduction).
• The lumen reading is a per minute count. On an unobstructed sunrise, it’s roughly around 30k lumens, meaning you’d only have to be outside less than 5 minutes. If it’s cloudy, you’ll need to stay outside longer.
• It’s ultimately about the light quality, so considering how close to sunrise and sunset are important factors.

I spent the past year waking up at my “natural” time with no alarm clock. It usually ended up being somewhere between 8:30 to 9:30am, a bit late for my liking. I used an alarm clock to force myself up around 7am and paired it with what I learned in the Huberman Lab podcast: getting lumens in the morning and sunset while metering my pre-bedtime device consumption. Within a week, I woke up without an alarm clock before 8am. 

This is a fun science experiment you can test for yourself with no sketchy supplements. The worst thing that happens is you’re stuck watching a few stupid sunrises or camping in the great outdoors.