Rising global temperatures due to climate change could mean a worse night’s sleep for your family. According to a report published in the journal
The investigators reviewed global sleep data collected from accelerometer-based sleep-tracking wristbands. The data, made anonymous before review, included 7 million nightly sleep records from more than 47,000 adults across 68 countries spanning all continents except for Antarctica.
The main report findings include:
- On very warm nights (greater than 30 degrees Celsius, or 86 degrees Fahrenheit), sleep declines an average of 14 minutes.
- Getting less than 7 hours of sleep also increases as temperatures rise.
- By 2099, suboptimal temperatures may cost 50 to 58 hours of sleep per person per year.
Sanam Hafeez, PsyD, a New York State-licensed psychologist, certified school psychologist, and director at Comprehend the Mind, says if your body reaches an uncomfortable internal temperature (either too cold or too warm), it can affect your sleep, but it’s mostly when it’s too hot that there’s an issue.
“More often than not, it’s warmth that can wake you up,” says Hafeez. “When you’re toowarm, it can make you toss and turn throughout the night, trying to get cooler.”
Warm temperatures in the evening and during the night negatively impact our sleep by causing more awakenings from sleep and less REM and slow-wave sleep (deep sleep), says Dr. Stephanie Stahl, an Indiana University Health Sleep Medicine physician. The optimal bedroom temperature during sleep is 60-67 degrees Fahrenheit for most people, says Stahl.
Dr. Shalini Paruthi, medical co-director at St. Luke’s Hospital, Sleep Medicine and Research Center, and co-chair of SLEEP 2021, says the warmer outdoor temperatures can mean warmer indoor temperatures, too. This is particularly the case since homes may be expensive to cool, she notes.
Longer days play a role in sleep health, too.
Light and darkness are key factors in how we regulate our sleep. Hafeez explains how exposure to light stimulates the area in the brain that controls body temperature and hormones like melatonin.
“As the sun sets, melatonin levels increase and stay elevated for about 12 hours. This directly affects how sleepy or awake we feel. So, the changing sunrise and sunset times in these warmer months can affect melatonin levels and when you start to feel sleepy at night. During the summer, the sun sets later, so you may not begin to feel tired until later,” says Hafeez.
The upside is that more sunlight hopefully encourages people to go outdoors for walks and exercise in sunlight, which is vital for resetting our internal clock every day, says Paruthi.
Stahl adds that sunlight in the morning can lead to improved daytime energy levels, a higher sleep drive at night, and better sleep quality. “So take advantage of the sunlight in the morning but avoid it in the evening.”
Hafeez says the following can help you get a better night’s sleep even on warm nights:
- Close windows and blinds during the day to keep heat out
- Limit bedding (cover with a thin blanket if anything)
- Choose cotton or other lightweight and breathable materials for pajamas
- Place a cool, damp cloth on your head (where heat leaves the body)
- Take a cold shower before bed
- Cool hands and feet down by keeping them outside the covers
- Limit exercise before you go to bed (to avoid having an accelerated heart rate that will keep you warm longer)
- Put refrigerated cooling gel pads in the bed at night
Satin sheets can also help you stay cool during the night, says Paruthi.
Daily routines, including regular mealtimes, bedtimes, and wake times, are also essential to sleep health in general, she says.
You may also want to consider blackout shades that can keep some sunlight warmth out of bedroom windows or an inexpensive box or small personal fan to help with temperature regulation. “Sleeping in a clean, dehumidified basement may also provide a cooler environment,” she adds.