How many times have you awakened on a hot summer night, drenched in sweat, your pajamas and sheets damp and clammy?
Being overheated, and sweating at night, are highly disruptive to sleep, keeping you from falling asleep and rousing you out of your sleep repeatedly throughout the night, depriving you of your most restorative deep, slow-wave sleep.
The temperature outdoors and the temperature inside your bedroom both play major roles in how soundly and well you sleep, throughout all the seasons. And so does your body’s own ability to manage and regulate its internal core temperature.
What does body temperature have to do with sleep?
The body’s
ability to maintain and adjust its core temperature is known as thermoregulation. Thermoregulation, like sleep-wake cycles and so many other of our physiological processes,
operates on a 24-hour circadian cycle. Falling and rising body temperature over the 24-hour day is an important contributor to the body’s sleep-wake cycle: dropping body temperature helps you fall asleep and stay asleep at night, and rising core body temperature stimulates alertness in the morning.
In preparation for sleep at night, the body pushes heat to the extremities. Blood vessels on the skin become larger in order to release heat. These physiological changes work to lower your core body temperature. A drop in core body temperature brings about feelings of drowsiness and helps usher in sleep itself. Body temperature stays low throughout the night before beginning to rise in the very early morning hours, helping prepare you to wake up and be active and alert.
To sleep well in summer and throughout the year, it’s important that your body be able to follow its natural daily temperature rhythm, including the evening and overnight cool down that helps to keep you in sleep mode until morning.
Supporting your body’s natural thermoregulation involves both priming your body for an evening temperature drop AND maintaining an optimal bedroom environment.
Setting up a temperate sleep environment
When we talk about
sleep environments and temperature, we’re talking about not only the room temperature but also the micro-climate of your bed. You can’t control the weather, but the steps you take to regulate the temperature of your room and your bed itself have a significant effect on how well you sleep—both the quality of your sleep and the length of your night’s sleep.
Too-hot environments impede the body’s thermoregulation and sleep—and so does a sleeping environment that’s too cold. Throughout the seasons of the year, you want to maintain a temperate climate in your room and your bed, to support your body in moving you from alertness to sleep and then back to alertness when you are ready to wake up.
What temperature is best for sleep?
Broadly speaking, the optimal room temperature for sleeping is around 67-72 degrees Fahrenheit. The precise right temperature for you is the one that enables you to fall asleep comfortably and stay asleep without waking, and to sleep without sweating or feeling chilled. For most people, that’s a temperature in the mid-to-upper 60s Fahrenheit.
In the summer, fans, air-conditioning, opening the windows at night to let a cooler breeze through the house are all warm-weather practices that can help your sleep. Closing curtains or draw blinds in order to keep the sun blocked and your bedroom cooler during the day, will help you maintain your bedroom at a temperature that’s comfortable for sleep.
How to build an ideal micro-climate
Things get a little more complicated when you’re working to maintain an ideal micro-climate in your bed itself. You’ve got to think about bedding layers, the heat that builds from your mattress, and the heat that’s produced by your bed partner.
People often simply sleep with too much bedding. Even in winter, I see people uncomfortable and disrupted from sound sleep because they’re buried in heavy blankets. I recommend investing in the highest-quality bedding you can afford, in multiple, lighter layers that can be easily added or removed to meet your individual needs and preferences, on a nightly basis if need be. Natural, breathable fabrics, such as cotton, silk and bamboo, are among the best for allowing air to circulate and your body to regulate its temperature throughout the night.
How does your mattress affect the temperature of your bed?
This can be one of the biggest challenges to maintaining an ideal bed climate. Foam mattresses in particular can trap heat throughout the night. As your body maintains contact with the mattress throughout the night, heat builds and you can wind up feeling sweaty, overheated, and restless. If you or your partner tend to feel hot during sleep, it may be worth it to consider
investing in a mattress that is designed with cooling properties (you can find them at a range of price points, and different mattress types).
There are also sleep systems for cooling that you can add to your existing mattress, to keep you and your partner sleeping comfortably and avoid overheating during the night.
I recommend this one the most often: it works by lowering your body temperature in the evening then warms up to help you wake up and feel alert quickly in the morning. It also allows two people the same bed to adjust their temperature independently.
Sleep cooling systems are one way to help address the effects of heat produced by a sleeping partner—and so is making sure you’re
sleeping on a mattress large enough for you both.
Priming your body for a pre-sleep cool down
You can protect and enhance your body’s evening core-temperature drop with a few sleep-friendly practices.
Time your exercise right. Exercise elevates core body temperature, and it
takes some time for the body to cool back to baseline—about 90 minutes, according to research.
Exercise too close to bedtime can keep you awake at night, by delaying the natural downturn in body temperature that helps bring about sleep. Particularly if you have difficulty falling asleep at the start of your night’s rest, it’s a good idea to avoid everything but the gentlest forms of exercise—light stretching,
relaxed yoga, an after-dinner stroll—within 2-3 hours of bedtime.
Take an evening bath or shower. Love the feeling of relaxation that comes from an evening soak in the tub or turn under the shower? Without realizing it, you’re tweaking your body’s thermoregulation to your sleep-time advantage. A warm—
not scalding hot—shower in the evening will enhance the drop in body temperature that makes you feel relaxed and drowsy. The ideal time for this evening soak is about 2 hours before your bedtime.
Wear as little as possible to bed. If it’s comfortable for you, try sleeping in the nude, or wear light bedclothes made of natural, breathable fabrics or
moisture-wicking sleep performance blends that allow your body to release heat throughout the night and feel most comfortable.
To support thermoregulation and sound sleep, you do always want to make sure your extremities—your hands and feet—are warm. That might mean wearing socks in the winter, even if you’re otherwise sleeping in the buff!
When night sweats are about more than temperature
Warm weather and warm sleep environments are the most common reason for occasional nighttime sweating. But sweltering temperatures aren’t the only reason people experience night sweats.
Sweating during sleep has a range of potential causes. Several different types of medication can lead to night sweats. Anti-depressants, steroids, pain medication, hormones, and medication for diabetes are all types of drugs that have night sweats as a side effect. Often, night sweats are a consequence of another condition or ailment. Here are some of the more common conditions that are linked to nighttime sweating:
Menopause. Night sweats are a frequent symptom for women in menopause, and sometimes for women in
perimenopause. Women in menopause and perimenopause often experience sleep troubles, including night sweats, as a result of fluctuating hormone levels. The quality of sleep—and how well you feel during the day—can be deeply affected by night sweats and other menopause-related sleep disruptions. There are treatment options for women experiencing night sweats, including
cognitive-behavior therapy (CBT), which research indicates can help alleviate night sweats and other menopause symptoms.
Other hormonal changes and imbalances.
People with hormonal imbalances may sweat at night during sleep. Hormone dysfunction associated with diabetes and with thyroid disorders both can cause night sweats. The hormonal changes of puberty can also lead to night sweats—as can the hormonal fluctuations of pregnancy.
Obstructive sleep apnea. It’s a lesser-known symptom than snoring and daytime fatigue, but
night sweats are a common symptom associated with OSA.
Obesity. Being
overweight and obese can make night sweats more likely. Carrying too much weight can pose an array of other problems for sleep, including increasing risks for sleep disorders such as obstructive sleep apnea.
GERD. Gastroesophageal reflux disease—most commonly known as
acid reflux or heartburn—can bring about uncomfortable night sweats.
GERD is problem for sleep in general. People with nighttime heartburn are likely to experience disrupted sleep, including trouble falling asleep and staying asleep.
Anxiety and depression.
Stress and mood problems, including anxiety and depression,
may cause sweating at night that makes sleep uncomfortable. Anxiety and other mood disorders can be deeply disruptive to sleep, and
stress is among the most common causes of sleep trouble.
Night sweats can also be signs of other medical issues, including infection, adrenal dysfunction and cancer. With such a broad range of possible causes for night sweating, it’s important to speak with your physician if you observe any changes to the typical ways your body sweats at night—if you begin to sweat more frequently, or if your sweating increases in intensity.
