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Temp Minimum for Deep Work, Dopamine and Serotonin & 4 Brain Books

🤸‍♀️ Stretch 29

↑ Basically me for the past week. A Matisse in Musée de l'Orangerie, Paris.

Phew, I've been in a weird mental state over the last two weeks. I couldn't be bothered to read, write, share, or engage much. The first few days, I was resisting and grinding.

[!!!must.hit.arbitrary.self-imposed.writing.goals.no one.cares.about.but.me.!!@!!!] 

But then I decided to let it happen and appreciate this phase as a natural part of my weird human experience.

Motivation comes and goes in waves—and the best thing we can do?

Learn to work with our brains rather than against them.


  • Optimal time of day to do deep, mental work. Defining your temp minimum.

  • Dopamine & serotonin. Two reward systems to consider for true peak performance.

  • Get close to your brain. Four great books to start with.


My vision for this newsletter is to make all of us more curious about our own minds and bodies. Ultradian cycles are one of these cool features of our nervous system we can easily experiment with.

I've written about ultradian cycles before—the 90-120 minutes cycles in which we're biologically optimized for focus and attention.

In simple terms: our highs and lows of energy throughout the day. Those fluctuations are not random, and they're not some kind of personal failing either (I don't care what the voice in your head tells you! Don't listen!)

We all go through them, and we can use them to our advantage by purposefully timing when we do deep, mental work and when we do the menial, easy stuff.

The key question then is: how do you know when to schedule these 90-minute blocks of deep focus?

You'll be pleased to read I have an answer for you:

By calculating your temperature minimum.

No need to strap a thermometer to your body. We don't care about the actual temperature—we care about the timing.

Here's how it works:

  • For one week, track your natural wake-up time, so you have a sense of your average wake-up time. (If you have kids and this is impossible, ehhh... make a guess?)

  • Your body temperature is at its lowest about 2 hours before your typical wake-up time. Say your average wake-up time is 8 am, then your temperature minimum is around 6 am.

  • You can then be reasonably sure that your best work is going to be done anywhere from 4–6 hours after your temperature minimum. So if your temp minimum is at 6 am, an ideal time to begin focused work would be as early as 10 am, or as late as 12 pm, with 11 am likely being the sweet spot.

Once you hit your temperature minimum, your temperature will start to rise. That rise triggers the initial cortisol release, which wakes you up. Our body will continue to increase in temperature throughout the morning.

So what we're trying to do with this idea of adding 4-6 hours to your temperature minimum is catching the portion of the deepest slope of that temperature rise—which corresponds with focus and alertness.

Whether it’s 4, 5, or 6 hours will vary from person to person. This is highly personal. You want to experiment with this.

Or if you're like me, you might wake up and feel very alert first thing in the morning. I can do my most focused work almost immediately after waking (assuming I've had a good night's sleep.) So if that's you—ignore everything I've just explained. Leverage that early morning time.

But if you’re someone who struggles to find focus in the morning, definitely let your physiology and this rise in your body temperature support your effort to focus—rather than forcing yourself to do your best work at times of day when your physiology is directing your body and brain towards defocus and being more lethargic.


I had many goals for February and March in terms of writing and Creative Experiments. But my brain and body had different plans, no matter how much I tried to push myself.

I tried to be unemotional about this and look at my physiology to understand what was happening.

I guess it's a lesson I have to learn again and again, but "peak performance" has nothing to do with going at 100% at all times.

A true high performer is someone who is able to toggle between the two reward systems of dopamine and serotonin, two of our most important neuromodulators.

At this point, the word dopamine feels overused, which is a shame because it's important to understand.

Dopamine is vital when it comes to motivation, pursuit, and goal-setting. We have a natural baseline of dopamine, and it can spike or drop based on what we do and even what we think.

Maintaining sufficient baseline dopamine levels is important to sustain day-to-day motivation. We don't want the baseline too low or too high. When dopamine is low in our system, we simply won't put in the effort to obtain or reach a goal.

That's what I was noticing in myself. No matter how much I tried to bully talk myself into it, I just couldn't bring myself to do any writing. Everything just felt... meh.

In the Huberman Lab interview with Dr. Kyle Gillett, they use the analogy of a 'dopamine wave pool':

The depth of the pool is the reservoir of dopamine, and the waves are the motivation.

When you're pursuing a goal, and you're putting in a lot of hard work for days and weeks on end, you're generating waves in that pool.

When the waves are too big (too much excitement and motivation and pursuit for too long), the water sloshes out of the pool, lowering the reservoir of dopamine. The waves can't keep repeating themselves, and so within a few weeks, the dopamine reservoir is depleted.

The reservoir is exhaustible, but it's also renewable.

The only challenge there is:

After those big waves in dopamine, the baseline drops below its initial level. It's as if the pool has gotten deeper and it takes much longer to fill back up.

Over the last few months, I've been splashing around like a madwoman in my dopamine pool. High expectations, constant stimulation. Even when 'taking a break,' I'm expecting myself to do something productive, usually related to reading a book or listening to a podcast, and of course, take notes on what I'm learning so I can write about it. 🤦‍♀️ It's caught up with me. That's okay. It's actually a good experience to go through and has given me a new insight into my body.

Anyway, back to our empty dopamine pool. Huberman talks about 3 ways to replenish dopamine:

  • Quality sleep + early morning sunlight: crucial for a sense of motivation. Morning sunlight, as close to waking up as possible, gives you a dopamine boost.

  • Non-Sleep-Deep-Rest: guided body scans shown in studies to replenish dopamine and cognitive abilities, and even make up for lost sleep. Good to do a few times per week, not only when exhausted or unmotivated (before the pool is empty!) I really like this 23 mins session.

  • Manage your dopamine schedule: be aware of dopamine peaks and layering in too many things that stimulate dopamine. None of these are bad in isolation, but we get in trouble when stacked together—caffeine, social media, music, food, etc.

So that's dopamine.

I also mentioned serotonin—the other important feel-good neuromodulator.

When serotonin is high in our system, we feel comfortable and calm. There's a feeling of "enoughness" with what we have in our immediate environment. Think of a nice family meal, meeting a friend, or holding your partner. Serotonin doesn't stimulate action but stimulates stillness—as opposed to dopamine which is all about the pursuit of things outside of us.

Research shows that a key way to tap into your serotonin reward system is by expressing and receiving gratitude. This is not woo-woo stuff. Recognizing and, in particular, writing down things you are thankful for or that delight you, have a positive effect on the serotonin system. I've been doing this for a while with my Positivity Journaling and especially given the last two weeks, will continue to make sure I do it every day.

So, all of this to say:

The key is in balancing our dopamine system and serotonin systems. We can't just be hard driving and in pursuit all the time (overplaying the dopamine system), but we shouldn't sit around and simply appreciate we're alive either (overplaying the serotonin system). It's about finding ways to toggle back and forth between different activities that play into these two very important reward systems we all have.


I can't think of a better way to spend your time than learning about your brain.

See yourself as a amateur neuroscientist of your own brain. :)

4 great books to get started:


I've started partnering with Meco—a newsletter reader app specifically designed for Gmail users. Meco connects directly with your email account and then takes your favorite newsletters out of your inbox and into your Meco app, where you can group them and customize your reading experience.

2 reasons why I recommend it:

  1. I love newsletters and am subscribed to... quite a few of them. This means my poor inbox gets overwhelmed sometimes, so having a separate space to read the latest newsletters is great - plus, it looks super clean.

  2. I've been very conscious of my "digital habits" lately. With an app like Meco, you can time-shift your consumption. Instead of immediately reading every newsletter as it comes in (when you're supposed to be paying attention in that Zoom call, for example), you save it and read it later that week. This small change of habit lets you escape the reactivity loop, which most of us are on when we're constantly reacting to what's in front of us.

It's entirely free and available on iOs and web (desktop).

Worth giving it a try if you're a newsletter nut like me. 🙋‍♀️

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