#13: Temperature - Part 1

01/17/22 • 9 min

1 Listener

In today's episode, Matt reveals how 1) your own temperature and, even more precisely, 2) the temperature of different parts of you, as well as 3) the temperature of your bedroom, can change how well or how poorly you sleep at night.

Matt describes the basic physiology of how your brain and body needed to drop their core temperature by about 1 degree Celsius, or about 2 to 3 degrees Fahrenheit, for a person to fall and stay asleep across the night. This is the reason why we will always find it easier to fall asleep in a room that's too cold than too hot because the room that's too cold is at least taking you in the right temperature direction for good sleep at night.

Matt teaches us that, ironically, one important way to drop your core body temperature is to warm up your extremities, specifically your hands and feet. He explains that it's one of the key ways your body regulates temperature.
To drive his point home, Matt points to research showing that if you gently warmed the paws of rats, it encourages the blood to rise to the surface of the skin of those paws, away from the core of the body. By emitting heat away from the body's center, it drops core body temperature rapidly, and as a result, the rats drifted off to sleep far faster than was otherwise normal.

Matt complements all this with a study in humans using a whole-body temperature sleeping suit, a little like wetsuit, but with tubes throughout that can warm or cool different parts of the body with warm or cool water.
In the first series of studies, researchers selectively warmed the feet and the hands by just a small amount, which caused a rising of the blood to the surface of the skin. As they warmed the body's extremities, the core temperature of the participants dropped, and the upshot was that these healthy individuals were falling asleep 20% faster than was normal.

In the second round of studies, even more remarkable, if you manipulate the temperature in this way in older adults, they will fall asleep 18% faster than typical, and insomnia patients will fall asleep a full 25% faster than usual with this same method.
The impact of temperature on sleep is therefore clearly significant, but there is even more to this thermal story, including how you can best wake up from sleep feeling alert, which is what Matt will discuss next episode.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The episode is sponsored by the wonderful folks over at Athletic Greens, who are providing a discount and free product if you use the link above. Athletic Greens is a comprehensive daily nutritional beverage containing 75 vitamins, minerals, and whole food-sourced ingredients, including a multivitamin, multimineral, probiotic.

So, head on over to Athletic Greens and get a free year supply of Vitamin D and 5 free travel packs today. Finally, if you have thoughts or feedback you’d like to share, please reach out on Instagram.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Previous Episode

#12: Melatonin

In today's episode, Matt takes us on a deep dive into melatonin. He covers four main topics: 1) what is melatonin? 2) how does melatonin work? 3) what does melatonin do, and *not* do, for sleep? 4) how can we think about melatonin supplementation?

First, Matt describes that melatonin is a naturally occurring hormone released by the brain. He gleefully notes that melatonin is often called, “the vampire hormone” as it comes out at night. In doing so, it signals that it is nighttime, which in turn helps schedule sleep.

Second, Matt explains that, during the day, light enters your eyes, and inhibits the release of melatonin. This absence tells your brain that it's daytime and time to be awake. Fast-forward to the evening, and the arrival of darkness, the floodgates of melatonin release open up. We need darkness in the evening to trigger this release, and, in turn, tell your brain that it's nighttime and time to sleep.

Matt highlights one significant problem of the present age: we live in a dark-deprived society. Many of us get too much artificial light, and not enough darkness. He shares a tip to dim down half of the lights an hour before bed and avoid screens.

Third, Matt elaborates on what melatonin does and does not do; that is, melatonin helps schedule the *timing* of your sleep but does not significantly change the *quality* of sleep. He uses the analogy of a race, where melatonin would be the official who begins the great sleep race but does not participate in the race itself.

Finally, Matt discusses supplementation. You can buy melatonin in certain countries to try to use it as a sleep aid. Based on scientific data across the past 15 years, Matt notes that melatonin isn't as effective as you may think: a recent meta-analysis discovered that melatonin only increases the speed with which you fall asleep by 3.9 minutes, and only improves your sleep efficiency by just 2.2%. This reinforces his point that the role of melatonin is primarily in regulating the timing of your sleep, not in sleep generation.
Matt states that melatonin is not well regulated as a supplement, and that the strength of melatonin that you buy is often unreliable. He describes a study that examined over 15 different suppliers. Strikingly, when tested, the concentration of melatonin within each pill ranged from 83% less to 478% more than what was stated.

Finally, Matt advises that the best way to optimize your sleep is to rely less on melatonin supplementation, and instead, focus on the basics we know make a real difference: sleep regularity, keeping your bedroom cool, getting darkness in the evening, get plenty of natural daylight during the morning, do some physical activity each day, and perhaps most importantly, address your stress and anxiety.
Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice, nor prescriptive in any way.

The sponsors of this week's episode are InsideTracker. They are offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.

So, make your way over to InsideTracker, and take advantage of this incredible deal on this valuable and remarkably convenient service. And, as always, if you have thoughts or feedback you'd like to share, please reach out to Matt on Instagram.

Next Episode

#14: Temperature – Part 2

In the previous episode, Matt described the role of temperature in helping us fall asleep. In this episode, Matt teaches us all about the role of temperature in helping us stay asleep across the night, and then more effectively wake up the following morning.

First, Matt takes us back to the body temperature suit experiments that were able to warm or cool different parts of the body. Matt explains that, using this same method, when you continue to cool the body throughout the first and middle parts of the night, enhance the ability of individuals to stay asleep more soundly across the night, increase the amount of deep sleep, and boost the electrical quality of that deep sleep.

Matt explains why a warm bath or shower before bed helps you sleep, perhaps for the opposite reasons you think. It is not that you get warm and toasty ready for bed. Instead, when you get out of the bath or shower, all of the blood races to the surface of your skin. As a result, your core body temperature plummets, enabling you to fall asleep faster and stay asleep more easily.

Matt also discusses how external ambient room temperature impacts our sleep at night. He notes that the optimal temperature for sleep at night for the average adult is between 16-18 degrees Celsius, or 61-65 degrees Fahrenheit, although everyone will be a little bit different, of course.

Finally, Matt explores the effect of temperature on waking up. He notes that as you move into those late morning hours of sleep, particularly as you start to enter the REM sleep-rich phases of your sleep cycle later in the morning, your central brain temperature rises significantly.
Indeed, it is in the last 30 minutes before people would naturally wake up in the morning that their body temperature starts to increase markedly. Matt goes on to describe how this increase in temperature is a signal that triggers the beginning of the awakening process.

Related to this, Matt notes that waking up can be challenging for many people, especially if you're not sleeping in synchrony with your chronotype. However, Matt suggests that one way you can facilitate the process of waking up more effectively is by trying to warm up the ambient temperature of the bedroom in the last 30 minutes before your alarm goes off. So if you have a smart thermostat, try to program it to increase the temperature to around 21 degrees Celsius or approximately 70 degrees Fahrenheit in the last 30 minutes before your alarm goes off.

The bottom line is that many of us don’t realize how important temperature is to falling asleep, staying asleep, and enjoying an enlivened awakening the next morning.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

The good people at InsideTracker are the sponsors of this week's episode, and they are generously offering 25% off any one of their programs for anyone who uses the above link. InsideTracker is essentially a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.