Sleep and Temperature

How Can I Sleep Better?


Welcome to the next entry of How Can I Sleep Better? Today we will be discussing temperature and the role it plays in the health of your sleep from the perspective of quality and quantity. We’ll talk about thermogenics, I know it’s a sciency word again but stick with me here, vasodilation, again stick with me, and other factors that significantly influence your sleep.

You may be asking yourself “What does temperature have to do with sleep?” “Is this guy about to force me to pay more for my electric bill?”. These are all solid questions that deserve an answer. There must be a balance between the data, behavioral interventions, and practicality. We know from available data if you stop drinking caffeine 12 hours before bed you will sleep better and we know that if you get 45 minutes of sunlight in the morning, that will improve your sleep, mood, emotional management, metabolism, and maybe get you closer to finding that genie in a bottle to grant you your 3 wishes. Ok, maybe the data doesn’t say anything about the last part, but the point is, there is a plethora of data out there telling you what will be beneficial for your health and it’s up to you to determine what is practical and what you can do. Maybe your electric bill will go up if you follow some of these sleep tips but is your sleep going to be better? Will your life improve?  I’ll try and give you the most information I can so you can answer these questions for yourself.

Have you ever been camping during the fall season? What about during the summer? If you have, you have undoubtedly noticed a difference in temperature throughout the day. At night, it gets cooler but during the fall, it’s much cooler and that can motivate you to bundle up. What’s interesting is if you were to pay attention to how well you slept in those two temperatures, you will likely find you slept better in the fall than in the summer. Why is this? Because the colder the ambient temperature, the easier and quicker it is to fall asleep. Pop quiz! What is the optimal temperature range for the average human to sleep? If your answer was between 65 and 67 degrees Fahrenheit, you’d be correct! When we sleep, our body goes through many different things to facilitate this. The most important thing for this post is decrease in temperature. On average, your internal body temperature needs to decrease by about 2-3 degrees Fahrenheit to fall asleep. This is why you will always find it easier to fall asleep in a room that is too cold versus a room that is too hot. When your temperature does decrease, it must stay that cold so you can remain asleep but when you begin to awaken at the end of your last sleep cycle, your core body temperature must rise. When you look at the research conducted on hunter gatherer tribes whose way of life has not changed for centuries, you will see that their sleep is dictated more by temperature than light, this is particularly true in the summer months. For those of us in modernity, temperature is often abandoned because its significance is not well understood or even known. People often attribute an influx of light to their awakenings and while that isn’t untrue, temperature also plays a critical role in this. 

“So, what does this mean? What tools can be utilized to help facilitate this temperature change?” I’m glad you asked! What this means is you need to have your bedroom cool at night to get good sleep both from a quantity and quality perspective. If you have a smart thermostat, try setting it to go down to 65 degrees about an hour before going to bed and have the temperature rise to whatever you normally set it to by about 30 minutes before you wake up. Try this for one week and see what it does to your sleep! Even if you don’t have a smart thermostat, setting it manually will be sufficient, though admittedly more annoying. If you don’t have central air where you’re living, try using something like a fan to bring down the temperature in your room. I keep my place at 65 when it’s time for bed and I have a fan to try and maintain that temperature. Outside of ambient temperature, there’s a couple of other tools you can use!

I mentioned a couple sciency words earlier, vasodilation and thermogenics, and both concepts can be very helpful when trying to obtain and maintain an optimal core temperature for sleeping. There is this misconception that when you take a hot bath or shower, you feel sleepy because you are warm and toasty. Heat relaxes you so people think it’s because of heat that you can sleep. They’re not wrong in thinking that heat helps you sleep but how it helps you sleep is actually the opposite of the popular belief. Vasodilation refers to blood rising closer to the surface of your skin and what that does from a temperature perspective is release the heat inside your body. With the blood comes heat and when heat leaves your body, it becomes colder, usually by about 2-3 degrees. Knowing what you know about core body temperature and its relationship to sleep, you also know that warming yourself up with hot water to cool your insides will facilitate better sleep latency and sleep maintenance. You may be thinking “If I need to be cool on the inside, why do we need blankets while we sleep? Why doe we wake up cold if we don’t have blankets sometimes?” This is because you need to maintain the body temperature that you have throughout the night so you can remain asleep. At a certain point, as your body temperature rises, the blankets will serve to trap that rising heat which will help you wake up. It seems like a strange process, but you need to heat yourself up to cool yourself down, you need blankets to maintain the temperature, and you need the core temp to rise to wake up. They all seem antithetical, but they work beautifully in a synchronistic fashion to help you sleep. The last term I mentioned earlier, thermogenics, refers to the way things like food and drinks impacts your internal temperature. When you eat food of any kind, it typically raises your temperature at least some because your body begins working to digest it. There are some foods, particularly carbohydrates or sugary foods, that are more thermogenic, so they raise your core temp more. This is one of the many reasons why the National Sleep Foundation suggests to not eat anything at least 2-3 hours before bed. You want your core body temperature down so try and avoid eating food but if you must eat food, eat something less thermogenic like protein. 

Thank you for reading this entry on temperature! Go forth and be cold! 


Fun sleep fact for your next party: The difference between the quality of your NREM, stages 3 and 4, sleep when your core body temperature is lower as opposed to when it’s higher is between 10% and 20%. The cooler you are, the better your deep sleep will be.