Tropical nights, characterized by minimum temperatures that do not drop below 20 degrees Celsius, have become a constant during this period, increasing thermal discomfort and affecting sleep quality. Fortunately, there are several methods you can use to rest when temperatures are extreme.

The optimal temperature for restful sleep is a crucial factor for our health and well-being, though it is often underestimated. Scientific research has demonstrated that ambient temperature plays an extremely important role in regulating our circadian rhythm, which controls our sleep-wake cycle and other important biological functions.

Most studies indicate that the ideal sleep temperature ranges between 15.5 and 19.4 degrees Celsius. These temperatures allow the body to cool down naturally during the night, a process essential for initiating and maintaining sleep, according to Healthline.com.

Our bodies naturally lower their internal temperature at night as part of preparing for sleep. A cooler environment facilitates this temperature drop and signals to the brain that it’s time to rest. Conversely, a too-warm environment can disrupt this process and lead to difficulties falling asleep, frequent awakenings and less restorative sleep.

Do you wake up in a sweat every morning? This is the grim reality for millions of people worldwide suffering from severe and unbearable heatwaves.

July is recorded as the hottest month ever on the planet and is likely the hottest period in the last 120,000 years, according to global climate authorities. Unfortunately, even harder times are ahead: a new study has found that the number of days of "dangerous heat"—defined as 39.4 degrees Celsius—will double by 2050 in mid-latitude regions, such as Europe and countries like China, Japan and the United States. Tropical areas might experience these temperatures for most of the year.

It’s not just the unbearable sun but also the nighttime temperatures that fail to drop as they should. Nights warm up faster than days, which is dangerous for nighttime sleep, a critical period during which the body and brain perform maintenance activities, such as repairing and removing old cells and generating new ones.

High nighttime temperatures have deprived people around the world of an average of 44 hours of sleep annually just in the first two decades of the 21st century, according to a 2022 study. Unfortunately, daytime naps and extended sleep during cooler nights do not seem to compensate for this lost sleep, researchers have found.

To achieve the best sleep quality, experts recommend sleeping in a cool room where the maximum temperature should be between 15.6 and 19.4 degrees Celsius. What if you can't achieve this temperature during a heatwave?

Studies have shown that high nighttime temperatures increase wakefulness and reduce deep and REM sleep (rapid eye movement), both critical for how the body repairs and refreshes itself during the night.

Learning how to better manage sleep issues during heatwaves could mitigate the negative impact on our health, according to a team of experts from the European Insomnia Network. Here are their main tips, along with some guidance from experts in the USA.

Stay hydrated: Drinking water during the day can help your body regulate its temperature better at night. Avoid drinking water an hour or two before bed as it may cause nighttime awakenings for bathroom trips, said Dr. Raj Dasgupta, a sleep specialist and associate professor of clinical medicine at the Keck School of Medicine, University of Southern California. Instead, "try sucking on ice cubes before bed".

Eat light foods: Consuming lighter foods during hot nights, especially at your last meal of the day, can help with better sleep, experts say. Avoid sugary and carbohydrate-rich foods, saturated fats and excessive fiber as the day progresses, as they can disrupt sleep, according to a 2016 study.

Dress lightly: Sleep naked or choose loose cotton clothes; avoid synthetic materials that can trap heat close to your skin.

Seek ways to cool your bedroom: If you are lucky enough to have a cooler period during the day, open windows and doors and turn on fans to ventilate the bedroom, then close them when the temperature rises. If there are no breaks from the infernal heat, such as a cool rain, pull the curtains and do everything you can "to keep the house and bedroom as cool and dark as possible, both day and night", suggested network experts.

Avoid alcohol: Drinking alcohol in the evening dehydrates the body and makes you prone to nighttime sweating, said Dr. Phyllis Zee, head of the sleep medicine department and professor of neurology at the Feinberg School of Medicine, Northwestern University, Chicago.

Relax: Allocate an hour or more before bed for calming activities, such as "reading a book, listening to a story or music. This could help with cooling down and relaxing", experts suggest.

Take a warm shower: Before bed, take a shower or bath with warm or cool (but not very cold) water. This can help reduce thermal stress and prepare for sleep.

"Your body temperature drops after you exit the shower or bath as your body adjusts to the cooler environment", said Dasgupta. "This decrease in temperature prepares the body for sleep because our body temperature has a natural circadian rhythm—our body is ready to cool down when you lie down and warm up when you get up".

Find the coolest place to sleep: Try to keep the bedroom as cool as possible, around 25 degrees Celsius, if you can. To do this, try using ceiling fans or electric floor or bedside fans, which use "up to 50 times less electricity" than air conditioning.

"Additionally, there are quite inexpensive ice-cooling fans that can be placed next to the bed", Zee said to CNN.

Maintain a regular sleep schedule: If you have a bad night's sleep, don't go to bed earlier the next night, experts say. It's important to stick to a regular bedtime to train your brain that it's time to sleep, regardless of the temperature.

If you wake up early and can’t fall back asleep within 15 to 20 minutes, get up and do something calming and mindless, such as folding laundry, until you feel sleepy again. If that doesn’t work, start your day as usual.

Exercise: Don’t skip your workouts, even if it's very hot. Try to exercise early in the morning when it's still relatively cool outside, experts suggest, as a key way to maintain a regular sleep and wake schedule.

Tips to cool down

The sweltering summer heat can be a real challenge, especially during tropical nights when temperatures remain high. Fortunately, there are several clever tricks that can help you cool down and enjoy restful sleep even on the hottest days. Here’s what you can do:

Block out the sun

To keep the indoor temperature low, it’s essential to prevent sunlight from entering. During the day, close windows, draw curtains or blinds, and use reflective films. These simple measures can significantly help maintain a more comfortable temperature inside your home.

Ventilate strategically

Evening or morning fresh air can work wonders for cooling your home. Open windows late at night or early in the morning when the air is cooler to create air currents. Make sure to close them again once the outside temperature starts to rise to retain the coolness.

Use smart fans

Strategically placed fans can improve air circulation in your home. An effective trick is to place a bowl of ice in front of the fan, so the air blown is cooler and more pleasant.

Turn off lights and electronics

Lights and electronic devices generate extra heat. Turn them off when they’re not needed to reduce the temperature in your home.

Cook strategically

Cooking during the day can add extra heat to your home. Opt for cold meals or cook outside on a grill to avoid additional heating indoors.

Stay hydrated

Regular water intake is essential for maintaining an appropriate body temperature. Drink plenty of water throughout the day, even if you’re not thirsty. Adding cucumber slices, lemon or mint to water can add a refreshing touch.

Take warm showers or baths

Although it might seem counterintuitive, warm showers or baths help regulate body temperature. Avoid cold water as it can cause vasoconstriction, making you feel even warmer afterward.

Apply cold compresses

Cold compresses applied to your forehead, neck, wrists or other pulse points can quickly cool down your body. You can use damp towels, ice packs or even frozen vegetables wrapped in a towel.

Wear loose and natural fabrics

Clothes made of cotton, linen or silk allow your skin to breathe and cool down. Avoid tight clothing and synthetic materials that can retain heat.

Avoid alcohol and caffeine

These substances can dehydrate your body, increasing the sensation of heat. Consume them in moderation or avoid them as much as possible on hot days.

Eat light and hydrating foods

Fresh fruits and vegetables, such as watermelon, cucumbers and leafy greens, are ideal for cooling down and hydrating. These foods help maintain adequate hydration levels and provide a refreshing sensation.

Avoid intense physical activity

On very hot days, try to reduce intense physical activity, especially during peak heat hours. Choose cooler times of the day for workouts or other strenuous activities.