Thermoregulation During Sleep: How to Avoid Sleeping Hot or Cold
Do you ever wake up at night feeling too hot or too cold? This happens due to poor thermoregulation during sleep, where your body struggles to keep an ideal temperature.
Feb 2nd, 2021 •
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.
Have you ever woken up because you’re too hot or too cold? Many people struggle with this problem nightly, experiencing daytime fatigue and memory troubles due to the lack of sleep. In order to regain control of your sleeping environment and body temperature, it’s helpful to understand what’s happening. The secret here is something called thermoregulation.
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 ability to control our body temperature is known as thermoregulation.
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 because it contains our vital organs. The core consists of the abdominal, cranial, and thoracic cavities.
- 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 influenced 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 you frequently wake up feeling too hot or too cold, your body may be struggling with poor thermoregulation,” says Dr. Dulka. “Poor thermoregulation can cause other problems like daytime fatigue and and memory troubles.”
Body Temperature Fluctuates Throughout the Day
Humans have an internal clock known as the circadian rhythm that regulates body temperature. 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.
“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.”
Sleep and Thermoregulation
Temperature regulation and sleep are intricately linked, and our circadian rhythm is largely responsible for both the hot/cold cycle and for the sleep/wake cycle.
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, our body temperature begins to dip in the evening. Once we go to sleep, this decrease in core temperature continues.
It is thought that by reducing the core temperature, our bodies have more resources available to allow for mental and physical healing and rejuvenation.
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 and is partly to thank for the energy that we feel in the mornings.
Related: Best temperature for sleep
Sleep Problems Caused by Poor Thermoregulation
Do you ever wake up because you’re too cold or too hot? This is caused by an inability of your body’s core temperature to get to where it needs to be.
“A common cause of poor thermoregulation is a sleeping environment that is either too warm or too cold,” says Dr. Dulka.
When we sleep somewhere that is 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 (rapid eye movement) sleep and other stages of sleep. You are 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.
Getting a Good Night’s Sleep: How to Avoid Sleeping Hot or Cold
“A possible treatment for sleep disorders includes fixing your sleeping environment like keeping your room temperature to a cool 60-67 degrees or even exercising shortly before bedtime,” says Dr. Dulka.
Other ways to keep you cool while you sleep includes:
- Wear light, breathable fabric like cotton
- Keep your room temperature between 60-67 degrees
- Adjust your bedding until you find what works best for you
- Use a firm mattress or a cooling mattress if you sleep warm
Additionally, there are other tricks that you can use to encourage the body temperature best for sleeping:
- Exercise 4 or more hours before bedtime. This avoids a heightened core temperature at night
- Take a warm bath an hour or so before bedtime. The temperature drop that you’ll experience when you leave the tub mimics the natural drop in temperature that queues sleep.
Every night when you go to sleep, your core body temperature drops, allowing restoration and recovery. Maintaining the proper core body temperature is critical for optimal 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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