During a heat wave, our bodies undergo certain processes to help us cope with rising temps. While this makes it easier to tolerate hot days, it can seriously interfere with our ability to obtain high-quality sleep.
“In order to deal with heat, your body increases heart rate and blood flow to your periphery — the exact same things that happen when you’re anxious or stressed or otherwise physiologically on high alert,” Valerie Stone, Ph.D., PSY-C, a sleep therapist and founder of A Good Night’s Sleep in Arvada, Co., told Mattress Clarity via email. “This gets in the way of sleep.”
So what should people do when a heat wave hits? Here’s a closer look at how heat disrupts sleep — plus what to do about it.
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Why Heat Disrupts Sleep
To understand how heat can impact sleep, we first need to understand the body’s nervous system.
“Our nervous system consists of two parts: the sympathetic system and the parasympathetic system,” Dr. Anil Rama, MD, Medical Director and Founder of Kaiser Permanente’s tertiary sleep medicine laboratory and Adjunct Clinical Faculty at the Stanford Center for Sleep Sciences and Medicine, told Mattress Clarity via email. “The sympathetic (or “fight and flight”) system is generally active during the day, whereas the parasympathetic (or “rest and digest”) system is usually more active at night.”
How does all this relate to sleep?
“Any process that increases the activity of the sympathetic nervous system makes sleep more difficult,” Rama says. “Heat has been demonstrated to increase the activity of the sympathetic nervous system.”
This is becoming a bigger issue as climate change raises temperatures around the planet. “If climate changes produce more heat waves, sleep of all creatures will be affected,” Rama told us.
Stone says there’s already evidence that this is happening around the globe. “Expect to see more studies coming out in the next few years,” she told us.
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How to Sleep Better When It’s Hot Out
“If you have air conditioning, the most obvious solution to beat the heat when you’re trying to sleep is to turn it down,” Dr. Kent Smith, founding director of Sleep Dallas and President of the American Sleep and Breathing Academy, told Mattress Clarity via email. Smith says individuals may want to adjust the A/C to as low as 60 degrees.
If A/C isn’t an option, then Smith recommends other strategies for keeping the room as cool as possible. “Hanging blackout curtains and a ceiling fan, or investing in a few box fans, can help lower the temperature in your bedroom to a comfortable temperature,” he says.
Switch up the sleeping space.
Many people’s bedrooms are in the upper stories of their homes, but the higher one’s bedroom the hotter it’s likely to be — so a change of scenery may be needed.
“Sleep in the basement, or the lowest floor of your home,” Stone says. “Being lower means being cooler.”
Optimize clothing and bedding fabrics.
“Satin, silk and polyester are prime for pulling heat away from your body while you sleep, and lighter shades can even help promote airflow throughout a bedroom,” Dr. Sujay Kansagra, Mattress Firm’s sleep health expert and the director of Duke University’s Pediatric Neurology Sleep Medicine Program, told Mattress Clarity via email. “Your bed and sheets can often be the biggest culprits of heat build-up that make it hard for you to get the cool sleep you need, so make sure you are using fabrics that breathe — whether that be in what you wear or what you sleep on.”
If sleeping on a foam mattress, add some layers for breathability.
“Put extra cotton layers… between you and the foam top of your mattress to increase breathability,” Stone says. She suggests using layers that are thicker than a sheet, such as cotton towels.
It may also be helpful to invest in a mattress specifically designed to help people sleep cool.
Cool down the extremities.
“Your extremities are pulse points that retain and emit heat,” Caleb Backe, CPT, a health and wellness expert and a member of the Mattress Clarity Expert Network, told us via email. Take advantage of this knowledge to enjoy some extra cooling.
“Immerse your feet in cold water before crashing for the night,” Backe suggests. “This will help to bring down your body’s internal temperature, which not only cools you down but also optimizes sleep quality.”
It may also be helpful to take a cool shower before bed, Smith told us.
Stay hydrated.
“Consume water regularly throughout the day to keep your body properly hydrated,” Smith says. “Feeling parched may disrupt your sleep by making you more prone to snoring. Slow down your water intake a couple of hours before bed to avoid waking up during the night to use the restroom.”
Additionally, it’s a good idea to limit the consumption of alcoholic beverages. “Alcohol is not only troublesome to the body’s sleep patterns, but it can also increase your body’s core temperature,” Smith told us.
Get outside in the morning, when it’s cooler.
Smith says that spending time outside during cooler mornings provides an opportunity to reset the body’s circadian rhythms.
“This will increase your sleep drive in the evenings when you need melatonin release and proper preparation for sleep,” Smith told us.”
Trust the body.
“Getting to sleep and staying asleep are all about balancing your body’s sleep drive vs. your body’s alertness drive — sleep happens when your sleep drive is higher than your alertness drive,” Stone says. “Heat changes the equation, but your sleep drive will still win out in the end when you’re sleepy enough.”
Stone emphasizes that it’s important to trust this sleep drive even when it’s hot. “Worrying about how heat will affect your sleep only makes your body more alert, and interferes with sleep,” she says.
Those who find themselves lying awake for more than 20 or 30 minutes, Stone says it’s a good idea to “get up and do something soothing and relaxing, without bright lights, until your eyelids feel heavy again.”
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