Thermoregulation During Sleep: How to Help Your Body Maintain an Ideal Temperature at Night
Jul 1st, 2022 •
Expert Insights from Dr. Brooke Dulka, a medical writer and neuroscientist who received her Ph.D. in biological psychology from the University of Tennessee, and she is currently a postdoctoral researcher at the University of Wisconsin-Milwaukee where she studies the neurobiology of memory.
Do you wake up in the middle of the night feeling too hot or too cold? Many people struggle with these temperature-related sleep interruptions, which can cause problems that carry over to your waking hours.
“If you frequently wake up feeling too hot or too cold, your body may be struggling with poor thermoregulation,” says Dr. Brooke Dulka, a neuroscientist and medical writer. “Poor thermoregulation can cause other problems like daytime fatigue and memory troubles.”
Before you can regain control of your sleeping environment and body temperature, it’s helpful to understand the reasons why people wake up sweating or shivering.
What is Thermoregulation?
As you know from being outside on a hot or cold day, our bodies work to maintain an optimal temperature. We use evaporative cooling for heat loss in the form of sweat when it’s too hot, and we use thermogenesis in the form of shivering when it’s too cold. This process of controlling our body temperature is known as thermoregulation.
How Our Bodies Turn the Temperature Up or Down
When it comes to thermoregulation, our bodies consist of two parts:
- The core: Our core temperature, or internal body temperature, is the most critical when it comes to our health and survival since this part of the body contains our vital organs. The core consists of the abdominal, cranial, and thoracic cavities (stomach, head, and chest).
- The shell: Our shell temperature, or external temperature, is more variable than our core temperature. It consists of the outer part of our bodies, such as our muscles and skin, which are more easily affected by environmental conditions.
During thermoregulation, the priority is keeping the core temperature stable. When it’s cold out, blood vessels are constricted to avoid losing heat from the core to the extremities. When it’s hot out, our blood vessels dilate to allow heat to escape from the core to the extremities.
If the process reaches the point where you start to sweat or shiver in your sleep, it can be enough to jolt you awake.
Why Does Your Body Temperature Drop When You Sleep?
Thermoregulation takes place while we sleep as well as when we’re awake. During every 24-hour period our body temperature falls and rises, with warmer temperatures during daytime (waking hours) and lower temperatures during nighttime (sleeping hours).
When our core temperature is higher, we tend to feel more energized, and when it dips, we can feel tired and sluggish. This is also why skin temperature feels colder during the night than during the day.
Temperature regulation and sleep are intricately linked. The reason why it’s easy to fall asleep at night and harder during certain times of the day is because of our core body temperature.
Thanks to our circadian rhythm—an internal “body clock”—our body temperature begins to dip in the evening. Once we go to sleep, this decrease in core temperature continues. Our core body temperature reaches its coldest point around 5 a.m., and from there, slowly begins to rise. This increase in body temperature encourages us to wake up.
“The pre-optic area/anterior hypothalamus (PoAH) region of the brain plays an essential role in thermoregulation and actually contains heat-sensitive neurons,” explains Dr. Dulka. “How does this relate to circadian rhythms? Well, the master circadian clock, the suprachiasmatic nucleus which is also in the hypothalamus, sends neural projections to the PoAH; it is through these connections that the circadian system is thought to influence sleep/wake cycles and daily temperature rhythms.”
Related: Best Temperature for Sleep
Push and Pull of Natural Processes
One thing that can interfere with thermoregulation is, interestingly enough, a normal part of the sleep process: rapid eye movement (REM) sleep. Thermoregulation is inhibited during the REM stage of sleep, making the body more sensitive to changes in external temperature.
There’s also a connection between sleep, metabolic rate, and thermoregulation. The human body’s metabolic rate, the amount of energy it uses in a certain period of time, goes down by an estimated 15% during sleep. However, the metabolic rate increases during thermoregulation.
The interaction of these processes, and more, suggests that body temperature during sleep is a complex balancing act. When it’s thrown out of balance, interrupted sleep is one of the effects.
Tips to Avoid Sleeping Hot or Cold
When we sleep somewhere that’s too warm or too cold, our bodies will eventually run into a problem maintaining their optimal core temperature.
If you’re too warm during sleep, it will encourage increased alertness levels and disrupt REM sleep and other stages of sleep. You’re also likely to wake up if the temperature changes drastically and your body can’t adapt quickly enough. Conversely, too cold of a sleeping environment will cause a similar disruption as your body awakens to find a way to warm itself.
“A common cause of poor thermoregulation is a sleeping environment that is either too warm or too cold,” says Dr. Dulka. “A possible treatment for sleep disorders includes fixing your sleeping environment, like keeping your room temperature to a cool 60-67 degrees.”
What if maintaining that ideal temperature range just isn’t feasible, though? If you’re worried about the cost of cranking the thermostat up and down, you can try these tips to keep from getting too toasty or too chilly.
If You Sleep Hot:
- Adding blackout curtains, a fan, and a dehumidifier can make your bedroom cooler and less stuffy, especially when you need to sleep cool in the summertime.
- Wear light, breathable fabrics like cotton to bed—or if you’re more of a free spirit, wear nothing at all.
- Use a firm mattress or a cooling mattress. If you have a memory foam mattress that tends to sleep hot, you can use cooling accessories and other methods to help make it feel cooler.
- Set an exercise deadline at four hours before bedtime. Limiting your physical activity late in the day helps give your core temperature time to cool down.
If You Sleep Cold:
- Wear cold-weather pajamas made of flannel, fleece, and similar materials that help keep you warm throughout the night.
- Don’t forget about your feet. Since you can easily lose body heat through your extremities, even a lightweight pair of socks can do wonders on chilly nights.
- Use bedding made of winter-friendly materials, including warm sheets and comforters.
- Try layering, with your clothes as well as your bedding. Multiple layers can be more effective at keeping you warm without letting you overheat.
Good Sleep is a Matter of Degrees
The drop in core body temperature while you sleep helps facilitate restoration and recovery. Maintaining the proper core body temperature is critical to an optimal sleep routine, both in terms of quantity of sleep and quality of sleep.
If you struggle to sleep through the night, use the tips above to help support thermogenesis and keep your body temperature where it needs to be for a restful night’s sleep.
Dr. Brooke Dulka is a medical writer and neuroscientist. She recieved her Ph.D. in biological psychology from the University of Tennessee, and she is currently a postdoctoral researcher at the University of Wisconsin-Milwaukee where she studies the neurobiology of memory.
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