Find Your Temperature Minimum to Defeat Jetlag, Shift Work & Sleeplessness | Huberman Lab Podcast #4 Flashcards
Recap about “perfect schedule”
We as humans are designed to sleep at night and be awake during the day. We want to look at lights during the day en look at darkness when it becomes night. In the morning look at sun light of 100,000 LUX in the time frame of 9 AM-10AM given that you wake up between 5 and 8.
How light’s effects are different during the day
Early at the day a lot of photon energy is needed to set the circadian clock and tell your brain and body its morning. Do this before the circadian “death zone” in the middle of the day, 9-10 am. However, it takes very little photon energy to reset and shift our clock after 8:00 PM- 4 AM, so avoid light between these hours. You can influence this by watching afternoon light of the sun, so you have a bit more wiggle room to watch screens and overhead lights even at night without disrupting your circadian clock.
What is jetlag ?
Let’s talk about what jet lag is. Okay well, I promised that I wouldn’t get too dark with all the terrible things that can happen with jet lag, but I’m about to get dark. There are quality peer reviewed papers showing that jet lag will shorten your life. It will kill you earlier. I guess it means you’ll die earlier. It doesn’t actually kill you necessarily. Although there are many cases where tourists end up stepping in front of buses, especially in countries where the cars and buses drive on the opposite side of the street that they’re used to,
who are jet lagged and lose their life that way.
And turns out that jet lag has two elements, travel fatigue and time zone jet lag.
- Time zone jet lag is simply the inability of local sunlight and local darkness
to match to your internal rhythm, this endogenous rhythm that you have.
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Jetlag gets worse with age
Why is there a difference between a jetlag from going west and east?
We’ve talked before about the autonomic nervous system, this set of neurons in our spinal cord and body and brain that regulate our wakefulness and our sleepiness. Turns out that human beings, and probably most species,
are better able to activate and stay alert than they are to shut down their nervous system and go to sleep on demand. So if you really have to push, and you really have to stay awake, you can do it, you can stay up later. But falling asleep earlier is harder. And that’s why traveling east has a number of different features associated with it, that because you’re traveling east
you’re trying to go to bed earlier, you know. As a Californian, if I go to New York city, I’ve got to get to bed three hours early and wake up three hours early, much harder than coming back to California and just staying up a few more hours. And this probably has roots in evolutionary adaptation where under conditions where we need to suddenly gather up and go or forge for food, or fight, or do any number of different things, that we can push ourselves through the release of adrenaline and epinephrin to stay awake. Whereas being able to slow down and deliberately fall asleep is actually much harder to do. So there’s an asymmetry to our autonomic nervous system that plays out in the asymmetry of jet lag.
Why is temperature such an important effect for your body?
What you’re going to find is that you have a low point, the temperature minimum, and then your temperature will start to rise,
you’ll wake up about two hours later. Then your temperature will continue to rise into the afternoon it will peak, maybe a little trough, sometimes that happens, and then it’ll start declining slowly as you approach nighttime. There are things that will disrupt that temperature pattern. Saunas, cold baths, intense exercise, etc. Meals tend to have a thermogenic effect that increases temperature slightly little blips, but the overall cycle 24 hour cycle of temperature
And last time I talked about the seminal work of Joe Takahashi and others, who have shown that temperature actually is the signal by which this clock above the roof of your mouth in-trains or collectively pushes all the cells and tissues of our body to be on the same schedule. Temperature is the effector.
And once you hear that there should be an immediate, oh, of course, because how else would you get all these different diverse cell types to follow one pattern, right? A pancreatic cell does something very different than a spleen cell or a neuron, right? They’re all doing different things at different rates. So the temperature signal can go out and then each one of those can interpret the temperature signal as one unified and consistent theme of their environment.
How to use your temperature minimun to delay and advance your carcadian clock?
Okay, so now you know how to get your temperature minimum. Your temperature minimum is your absolute reference point
for shifting your circadian clock. Whether or not it’s for jet lag, or shift work, or some other purpose. Here’s the deal. If you expose your eyes to bright light in the four hours, maybe five or six, but in the four hours after your temperature minimum, your circadian clock will shift so that you will tend to get up earlier and go to sleep earlier in the subsequent days, okay? So it’s called a phase advance, if you’d like to read up on this further. You advance your clock, okay? However, if you view bright light in the four to six hours before your temperature minimum, you will tend to phase delay your clock. You will tend to wake up later and go to sleep later.
Okay, I’m going to repeat this because there’s so much confusion out there and people talk about circadian time and all this. Find your temperature minimum. I tend to wake up at about 6:00 AM, sometimes 6:30, sometimes seven. It depends a lot on what I was doing the night before
as I’m guessing it does for you. But that means that my temperature minimum is probably somewhere right around 4:30 AM.
Which means that if I wake up at 4:30 AM and I were to view bright light at 4:35 AM, I’m going to advance my clock. I’m going to want to go to bed earlier the subsequent night and wake up earlier the subsequent morning. And as I shift my wake-up time, my temperature minimum shifts too, right? Because each time we shift our wake-up time our temperature minimum shifts, assuming that wake up time shifts more than 30 minutes or an hour, okay.
If I were to view bright light in the four to six hours before 4:30 AM, guess what? The next night I’m going to want to stay up later and I’m going to want to wake up later the subsequent morning.
How to deal with your carcadian clock during traveling
Am I trying to advance my clock or delay my clock? Remember viewing light, exercise and eating
in the four to six hours before your temperature minimum will delay your clock. Eating, viewing sunlight, and exercising, you don’t have to do all three but some combination of those in the four to six hours after your temperature minimum will advance your clock. And this is a powerful mechanism by which you can shift your clock anywhere from one to three hours per day, which is remarkable. That means your temperature minimum is going to shift out as much as three hours, which can make it such that you can travel all the way to Europe
and in as long as you’ve prepared for a day or so by doing what I described back home
and then doing it when you arrive, you can potentially accomplish the entire shift within
anywhere from 24 to 36 hours
What is the difference between traveling east or west
East:
Start shifting your clock when you are at home by watching the light, exercising, or eating in the 4-6 hours after my min temperature, hereby I am able to change my circadian clock to 1-3 hours a day.
West:
Avoid going to bed an napping, and use light exercise caffeine in your advantages by postponing the nap.
shift work
If there’s one rule of thumb for shift work, it’s that if at all possible, you want to stay on the same schedule for at least 14 days, including weekends. Now that should immediately cue the non shift workers to the importance of not getting too far off track on the weekend, even if you’re not a shift worker. So sleeping in on Sunday is not a good idea.
And he was really emphasizing this point because shift work where people are doing the so-called swing shift, where they’re working four days on one shift and four days on or another,is extremely detrimental to a number of health parameters. It gets the cortisol release from the adrenals really out of whack. And there’re these cortisol spikes at various hours of the day, it messes up learning, it really disrupts the dopamine system and wellbeing. It is a serious, serious problem.
