30-Day Rest + Refresh Reset: Days 22-24

Sweating the details: how temperature impacts sleep

Small adjustments to our body temp can have a big impact on how we sleep. Photo by Maddi Bazzocco

When most of us think about sleep and body temperature, we tend to think about cozying up under piles of covers or tossing off sweat-drenched sheets. But body temperature impacts our circadian rhythm, the (roughly) 24-hour internal clock that regulates various biological functions, including our sleep-wake cycle

We actually have two types of body temperature: The temperature of our internal organs, our core, and the temperature of our skin, muscles, and outer body, or shell¹. Our core temperature changes within a narrow two-degree range throughout the day according to our circadian rhythm. Our shell temperature fluctuates more wildly based on things like exercise, stress, and environment (e.g., that pile of blankets). 

Core and shell temperature work together. Generally, when our shell temperature gets hot, nerve endings on the skin send the brain a message to start processes like sweating that cool our core temperature. And, when our shell temperature is cold, those nerve endings tell the brain to keep the core warm by decreasing blood flow to the skin, allowing it to pool in our torso and keep our vital organs warm (this is also why fingers and toes are the first to feel cold).

Here’s why this matters to our sleep: Typically, our internal thermostat is highest an hour or two before bed and lowest a few hours before we wake up. So small external adjustments to our shell temperature can impact our core and enhance our circadian rhythm. Here are a few to try: