Improving Sleep, Focus, and Learning Part 2

I wrote about light’s role in setting our circadian rhythm in the first post of this series. This post will focus on body temperature, an effector of our sleep and wake cycle. Much of the content comes from episode 4 of the Huberman podcast, some from the first 3 episodes. This background will give us ways to optimize our schedules and adapt to jet lag.

An uncle of mine, a neurosurgeon in Taiwan, took ice baths in the winter to train mental endurance and resilience. He also told me that based on teachings in Eastern medicine, there are certain times that are best for different activity types. Those dots connected as I wrapped up the 4th podcast in the Huberman lectures.

Our body temperature, even in the absence of light, food or exercise, follows a predictable cycle: temperature rises from a 24 hour low before waking, increases as we start the day, peaking in the afternoon before falling as we wind down the day. Our bodies warm up when we need to be awake and alert for work and cools down as we wind down the day.

The temperature minimum is the lowest body temperature during our 24 hour circadian rhythm. The actual temperature is not important: what’s important is when you hit your temperature minimum. When it occurs is more important for the purpose of tinkering with our schedules.

How do you find the temperature minimum? Average your wake-up times for a week. Wake-up is defined by when you get out of bed, so if you get up at 3am, but fall back asleep and emerge at 9am, then 9am is the wake-up time. The 2 hours before your average wake-up time is your temperature minimum. If your average wake-up time is 7am, your temperature minimum falls around 5am.

With temperature minimum as a reference point, two simple rules in regards to light:

  1. If you get light into your eyes within 4 hours after your temperature minimum (described in part 1 of this series), you phase advance your circadian rhythm, resulting in earlier wake-up the next day
  2. If you get light into your eyes within the 4 to 6 hours before your temperature minimum, you phase delay your circadian rhythm, resulting in later wake-up the next day

If your temperature minimum is 5am and you watch Netflix until 1am, it will push your schedule back. If you’re on vacation in Hawaii and your hotel room catches sunrise light, it’s likely you wake up earlier the following days.

Understanding temperature minimum also allows you to maneuver and adjust your schedule by shifting eat, exercise, and shower routines. Our bodies warm up when we need to be awake and alert for the day and cools down as we wind down into the night. With this mechanism, we can phase advance or phase delay our schedules. This is helpful if you want to improve productivity, fight jet lag or sleep better. 

Showers

A hot shower results in your body cooling down. This is why showering at night allows you to sleep better as your body cools down into sleep. Matt Walker describes how most of us are sleeping too warm in his book Why We Sleep and amongst many sleep tips, he suggests doing the hot shower at night to cool the body for sleep.

Cold showers do the reverse, which results in rising body temperature, and aside from the shock of having taken a cold shower, it wakes you up and helps you focus thanks to the release of norepinephrine (adrenaline). Regular use of cold showers, provided it is medically safe for you, is a great stress inoculation tool. I’ll cover the stress remediation tools in the next post in the series.

Exercise

Exercising results in a rise in body temperature. I’ve seen co-workers use the afternoon or lunchtime workout as a way to grab a second wind in the afternoon. Exercise has all kinds of obvious benefits, so I won’t cover that here. Keep in mind that working out too close to bedtime results in some trouble falling asleep since you are spiking your body temperature at a time it needs to be falling to induce sleep (of course, it’s not the only reason as an elevated heart rate also prevents us from being able to fall asleep). If you workout at night, this might be something to keep an eye on. 

Food

Meals are another way to regulate schedule. If you’re traveling to a different timezone, it helps to eat on the local meal schedule. Our gut also runs on the circadian rhythm, so meals are a helpful marker to adapt when traveling. Of course, eating too much results in literally a food coma, but changing what you eat can help with an after lunch crash. High carbs typically results in sleepiness while low or no carb won’t put you to sleep. My simple rule of low carb lunch, whatever-the-hell-you-want for dinner, has been a game changer. Diet is a giant wormhole for another time, but it’s worth considering how you respond to certain type of meals.

Ultimately, timing of light intake and body temperature are the key drivers for the sleep and wakefulness cycle. Exercise, eating, and shower can nudge temperature in certain directions if you want to make tweak your schedule for better focus at certain times of the day or fight jet lag. Understanding this mechanism allows you to adjust and experiment for the schedule that works best for you and because life sometimes feels like a sudden cold shower, it gives you a way to stay flexible.

Improving Sleep, Focus, and Learning Part 1

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. 


*Note: I have a question out to Dr. Huberman on how our eyes treat sunrise and sunset light differently. I will update this section when I learn more.

The Air Quality on Cloud's Rest

I imagine this is what the dinosaurs experienced. Not 45 minutes ago, we arrived at a lake just a few miles from Cloud’s Rest in Yosemite. We had set up a hammock, chairs, and relaxed into the beaming afternoon sun.

Then, someone turned on the cloudy gray setting, sequestering the sun, and started sprinkling ash on us as a prank. We packed up in haste, found camp, pitched our tents, and spent the majority of our lazy afternoon playing liar’s poker inside our tent. The smoke suffocated our moods as we considered wrapping up our trip and heading home, only three days into a week long backpacking trip.

The next morning, it looked as if someone emptied a fire pit on our tents. Ashen makeup glossed the alpine lake, clogging our water filters. Despite our somber environment, we chose to stick with our plan to hike up Cloud’s Rest that morning.

We hiked as the sky slouched with gray clouds as if a downpour threatened. No rain was coming. 

An empty summit surprised us. Recent California wildfires and smoke muted the usual throngs of Saturday hikers. After the jubilation of summiting, we took in the views with trail mix, dried apricots, and turkey jerky.

Instead of postcard vibes, we were entranced by a smoke signal floating across our view like a low San Francisco summer fog. Orange lights flickered. A wildfire, just getting started in the distance.

Not fog and not rain clouds...

I wrote about how California wildfires will worsen if we don’t take action. There are two policy options to address the megafire threat: (1) do controlled burns to clean out dead firewood or (2) continue to sequester fires, preventing natural burn, and allow nature to dictate record-breaking wildfires.

Either scenario means more smoke and days with poor air quality. The second scenario means more off-the-chart days, like 2020 wildfires turning San Francisco to an extended cut scene from Blade Runner.

PM 2.5 is fine particulate matter most common during wildfires. 2.5 indicates microns in diameter, so anything less than 2.5 microns is PM 2.5. For context, a human hair is roughly 50–70 microns in diameter. 

So these are the smallest and lightest pollutants. As a result, they stay in the air longer, increasing the chances we breathe them in. Alveoli air sacs in our lungs are responsible for oxygen exchange and our lungs interact non-stop with the outside world. Combine these two and this is how fine particulate matter enters your lungs and blood stream.

For adults, PM 2.5 is a cause of all sorts of issues from heart disease and decreased lung function. In our children, it affects all stages of development and overall lung health[1].

The World Health Organization’s guideline for PM 2.5 is 10 µg/m3 annual mean and 25 µg/m3 24-hour mean. If you map that to the Air Quality Index (AQI), it corresponds to an AQI of less than 50. In the San Francisco-Oakland-Hayward region, well over one third of days last year had an AQI greater than 50.

Exercising outdoors means faster air exchange. Exercising in poor air quality means pollutants enter our bodies at a faster pace.

Last year, there were stretches of days well above AQI scores of 300. We acclimated and thought, “hey, AQI is 100 outside, it’s not too bad, I can go for a jog”.

Don’t make that mistake! Stay inside with a HEPA air filter. Take it from the very smart people that slept outside while wildfire smoke blew into their faces.

As the afternoon crawled on, we were the only ones left on the peak. We decided to stay the night on the summit of Cloud’s Rest. With wildfires and smoke, we had the summit to ourselves on a Saturday night. When do you get a chance like that?

The setting sun looked like the last day on earth, spooky with a hazy orange beauty. We ate an apocalypse appropriate last meal: a dehydrated feast of chili, mac & cheese, and Pad Thai noodles. Satisfied stomachs sank into chairs as the air filled with the hum of the harmonica. Only mental tension broke the calm as we continued our liar’s poker battle.

We brushed our teeth as ash continued to fall, a funky combination. It felt as if we were inside Nature’s home while it was on fire, sleeping top bunk on the highest floor. Smoke filled the house, collecting near the ceiling where we slept.

I tossed and turned throughout the night, wondering if it would actually be possible to suffocate from this type of smoke exposure. With an N95 mask strapped to my face, I drifted off to sleep.

The next morning, we woke up to high definition blue and a vibrant morning light. Winds shifted overnight, blew away the nightmarish 24 hours of smoke around Cloud's Rest, and we were rewarded with an improved view of Half Dome, El Capitan, and Yosemite valley.

With this knowledge about wildfires and PM 2.5, I’m not sure I’d do it again. Next time, I’ll stay indoors to watch Free Solo on Netflix with my HEPA air filter and indoor air cleaning plants. 

[1] World Health Organization’s study of pollution on children’s health.

Edit: The World Health Organization revised their air quality guidelines on September 22, 2021, the first time in 15 years based on new evidence. The threshold for "good" air quality were halved.

California Wildfires

Ash fell onto the balcony of our apartment as smoke lowered onto the field in front of our dorms. It was 2007, my first year of college and the sky was burning over the campus of UC San Diego. We escaped up interstate highway 5, ironically headed to Alhambra, CA in Los Angeles, for cleaner air as wildfires licked the hills along the freeway. 

Fast forward 13 years to 2020 in California. Amidst a global pandemic, wildfires made headlines in California. This time, the entire state was covered in smoke for several weeks. Nowhere to escape. 

I was curious to know–will there be more fires? How much worse? Have we seen the worst after 2020 topped megafire records? Or is this the tip of the iceberg?

Some history: California is fire country. Fires are endemic to California and part of the natural landscape. 100 years of fire data shows us this much:

california fire history

Most of the state burned at one point or another. According to research about prehistoric California, at least 4.4 million acres burned annually: “Skies were likely smoky much of the summer and fall in California during the prehistoric period.”

Wildfires burned 4.4 million acres of our sunny state last year. Was this an outlier event? In the context of California fire history, 2020 turns out to be an exactly average year.

While 2020 was an average year in terms of acres burned, 6 of the 20 largest wildfires in California history burned last year. Average year in terms of acreage, outlier in terms of intensity, destruction, and disruption to the highest number of lives.

Sobering thought.

You might wonder, as I did, if last year’s fires means we’ve burned most of what could burn, lessening the threat of future fires. My optimism was extinguished when I learned California is sitting on a backlog of megafires waiting to happen:

“Between 1982 and 1998, California’s agency land managers burned, on average, about 30,000 acres a year. Between 1999 and 2017, that number dropped to an annual 13,000 acres. The state passed a few new laws in 2018 designed to facilitate more intentional burning. But few are optimistic this, alone, will lead to significant change. We live with a deathly backlog. In February 2020, Nature Sustainability published this terrifying conclusion: California would need to burn 20 million acres — an area about the size of Maine — to restabilize in terms of fire.”

We halted nature from running it’s natural course of burning firewood, creating a pile. of fuel prone to blow-ups like we saw in 2018 and 2020.

Assuming our backlog is static, we are left with roughly 15.6 million acres of dry powder after last year’s fire season. Of course, the backlog is not static. Trees and brush don’t suddenly take a break from turning into firewood.

Climate change has intensified California’s persistent drought situation, turning native bark beetles into the mortal enemy of California pines. The result? An estimated 129 million trees have died since 2010, much of it attributed to the drought and beetles. These dead trees were implicated for fueling last year’s fires, along with climate change driving increases in lightning storms. Regardless, the dry powder stash grows.

Extreme weather systems from climate change combined with California’s “sequester all fires” policy has one result: a powder keg of wildfires waiting to blow up. Simple math and respect for nature means another major wildfire, even bigger than the 2020 wildfires that lit the entire state on fire, is inevitable.

The San Diego fire that burned during our first year in college was the 14th largest in California history, burning just shy of 200,000 acres. A large fire. Over a decade later, we experienced a fire 5 times the size with larger ones to come. Well, that’s a scary thought.

The California Governor stated: “fires in California are caused by climate change”. A former President blamed California’s poor forestry management. Neither is wrong. But holding onto their party lines while ignoring the other side is how we’ll get into more trouble. If we can get away from the polarizing politics and combine the two statements, it would give us the exact platform to progress California in this domain.  

Note: ProPublica’s deep dive on the entire wildfire topic is worth a read as it covers the politics, federal budgets, mis-incentives, and the use of prison labor. 

A Collection of Unsolicited Advice

My sister graduated from college this year. What a weird year to join the real world. I thought I could give insightful advice as an older brother–you know, some nuggets of wisdom after 3 decades of life.

Instead, I procrastinated until the last day of the year. In place of writing something original, I combed through old notes and put together a collection of favorite essays and quotes. I wish I read, re-read, and internalized these sooner. 

Not all advice resonates the same way for everyone, so discard what doesn't work for you. The point isn't even to read all of it. Find the ones you relate to and read them slowly; linger on the ones that stick and make them a part of you. Putting useful thoughts into action is the hard part. 

On figuring out what you should work on

Derek Sivers, an entrepreneur and musician, on prioritizing: "When deciding whether to do something, if you feel anything less than 'Wow! That would be amazing! Absolutely! Hell yeah!' — then say 'no.'"

Chris Dixon, entrepreneur and venture capitalist, talking about hill climbing and different paths in life: "But the lure of the current hill is strong. There is a natural human tendency to make the next step an upward one. He ends up falling for a common trap highlighted by behavioral economists: people tend to systematically overvalue near term over long term rewards.  This effect seems to be even stronger in more ambitious people. Their ambition seems to make it hard for them to forgo the nearby upward step.

People early in their career should learn from computer science: meander some in your walk (especially early on), randomly drop yourself into new parts of the terrain, and when you find the highest hill, don’t waste any more time on the current hill no matter how much better the next step up might appear."

All of Paul Graham's essays are fantastic, I've read his writing for 10 years now, and it gets better. Work asks "what doesn't seem like work to you?", which is further explained in genius. How to do what you love is another classic. His essay for high schoolers is relevant for all of us. 

On failure and pushing through difficulty

Kobe Bryant on pushing through rehab after his Achilles injury: “I just go. Once I make the decision I am going to take this challenge on, I never waver and I never question the investment. I already made the decision. You have those painful moments, but you just keep on moving.”

Stephen Colbert on failure from his GQ interview shortly after taking over for David Letterman: “You have to learn to love the bomb. It took me a long time to really understand what that meant...It wasn't ‘Don't worry, you'll get it next time.’ It wasn't ‘Laugh it off.’ No, it means what it says. You gotta learn to love when you're failing...The embracing of that, the discomfort of failing in front of an audience, leads you to penetrate through the fear that blinds you. Fear is the mind killer.”

Reinhold Niebuhr: "Grant me serenity to accept the things that cannot be changed, courage to change the things which I can, and wisdom to distinguish one from the other.

Living one day at a time, enjoying one moment at a time, and accepting hardship as a pathway to peace."

On what other people think

Elizabeth Gilbert, Author of Eat Pray Love, on creating: "Recognizing that people’s reactions don’t belong to you is the only sane way to create. If people enjoy what you’ve created, terrific. If people ignore what you’ve created, too bad. If people misunderstand what you’ve created, don’t sweat it. And what if people absolutely hate what you’ve created? What if people attack you with savage vitriol, and insult your intelligence, and malign your motives, and drag your good name through the mud? Just smile sweetly and suggest – as politely as you possibly can – that they go make their own fucking art. Then stubbornly continue making yours.”

Tim Urban, Author of Wait but Why, on why you should stop caring what other people think. His long form essays are detailed and in-depth.

On wealth, but not money

Simple bulleted investing rules from Morgan Housel, a venture capitalist and great investing writer. One of my favorite investing writers I've read for a long time. His essays cover human behaviors around money, what we can learn from history, grand mistakes, and how to make sure you don't disturb compounding growth.

Another Paul Graham recommendation about making wealth.

A popular tweetstorm from Naval, philosopher, entrepreneur, and super angel investor, on how to get rich without getting lucky. It's the most concise summary on how to methodically approach the endeavor. 

General

There's no speed limit by Derek Sivers.

Sam Altman's life advice after turning 30. A lot of great things in here, I won't spoil it. 

One of my favorite writers, Nassim Taleb, giving a commencement speech at the American University in Beirut. The whole commencement is fantastic, but there's gold in the first 15 seconds: "For I have a single definition of success: you look in the mirror every evening, and wonder if you disappoint the person you were at 18, right before the age when people start getting corrupted by life. Let him or her be the only judge; not your reputation, not your wealth, not your standing in the community, not the decorations on your lapel. If you do not feel ashamed, you are successful. All other definitions of success are modern constructions; fragile modern constructions."

Taleb's book series is worth a read and Antifragile is my most re-read book.

The ever popular Steve Jobs Stanford Commencement Address: "Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart."

Bonus

Somebody just launched this: Alias - it's a directory of people and their content, all housed in one place. Right now it's heavily indexed on technology entrepreneurs but I suspect it will expand over time. There are a number of scientists and professors in there as well. Pick your rabbit hole carefully :-)