It's generally better to sleep in a cool room, ideally between 15-19°C (60-67°F), as a cooler environment helps your body's natural temperature drop, facilitating easier sleep onset and deeper, more restorative rest, while a hot room can cause restlessness and disrupt sleep stages. However, "too cold" can also be bad, with very low temperatures potentially increasing blood pressure or causing discomfort, so the key is a comfortably cool, not freezing, room, often achieved with warm covers.
The best room temperature for sleep is between 66 to 72°F. Your skin should ideally be between 88 to 95°F during sleep. The temperature under your bed covers should be around 90 to 93°F with 40% to 60% humidity.
Sustained living in a very hot room increases immediate discomfort, sleep loss and cognitive impairment; over time it raises risks of dehydration, electrolyte imbalance, cardiovascular strain, exacerbation of chronic disease, heat exhaustion and potentially fatal heat stroke--especially in vulnerable people.
Your body temperature decreases during sleep, and a cool, but not cold, room will help you settle down and maintain sleep throughout the night. There are scientific reasons why a cool room temperature is optimal for for good nighttime sleep. Your body's internal temperature shifts during a 24 hour period.
Disrupted sleep cycles
So sleeping in a cold bedroom is better for sleep, because overheating interrupts not just one but two crucial sleep phases; Deep Sleep and REM sleep. A lot goes on in the Deep Sleep and REM stages of our sleep cycle.
Cold air can cause pathophysiological responses (eg, vasoconstriction in the respiratory tract mucosa and suppression of immune responses) that increase the susceptibility to infections. Cold air inhalation was found to significantly affect the autonomic cardiac response without affecting sleep quality.
The 3-2-1 sleep rule is a simple wind-down routine: stop eating and drinking alcohol 3 hours before bed, stop working/mentally stimulating activities 2 hours before, and turn off screens (phones, TVs) 1 hour before sleep, helping you transition to rest by reducing stimulants and preparing your mind and body. It's often part of a larger 10-3-2-1-0 rule, which also adds no caffeine 10 hours prior and no hitting snooze (0) in the morning.
Sleeping too cold
“When we're cold, our body kicks into high gear to try and get us warm again,” says Dr. Drerup. Blood vessels become constricted, breathing becomes shallow and it puts extra pressure on our cardiovascular system to get our body temperatures regulated again, she adds.
Waking up drenched in sweat, even in cooler environments and during the winter, is a sign that you sleep hot. Excessive sweating is your body's way of telling you it's having trouble regulating your temperature. Our body temperature naturally fluctuates throughout the night as we go in and out of REM sleep.
The best temperature to sleep is cooler rather than warmer. Temperatures above 75 degrees and below 54 degrees can disrupt a person's sleep. A cooler temperature is the ideal environment to fall asleep and remain asleep throughout the night. Over a 24-hour period, our body temperatures naturally peak and decline.
The koala is famous for sleeping around 20-22 hours a day, which is about 90% of the day, due to their low-energy diet of eucalyptus leaves that requires extensive digestion. Other extremely sleepy animals include the sloth (up to 20 hours) and the brown bat (around 20 hours), with some snakes like the ball python also sleeping up to 23 hours daily.
Reasons for Sleeping Hot
Materials like polyester and memory foam can trap heat, while breathable fabrics like cotton and linen allow for better air circulation. Physiologically, individual metabolism rates and hormonal changes can increase body temperature, as can health conditions such as: Hyperthyroidism. Sleep ...
Heat exhaustion is a common condition that can occur when your body is exposed to high temperatures for extended periods. It happens when the body is unable to regulate its temperature properly, leading to dehydration, exhaustion, and other symptoms like headache and nausea.
For Australia, the ideal sleeping temperature is generally cool, between 15°C and 20°C (59-68°F), with some experts suggesting 17-19°C for deeper sleep, as a cooler environment helps your body's core temperature drop, facilitating better rest, though personal comfort varies. Temperatures above 24°C can disrupt sleep cycles, so using air conditioning, fans, or good ventilation helps, especially in warmer Australian climates, to keep the room cool enough for quality sleep.
Recognize the warning signs of hypothermia
According to The Sleep Charity, the ideal bedroom temperature for sleeping is 16–18°C. Anything over 24°C could be too hot and make you restless, while trying to sleep in a cold room with a temperature below 12°C could make it harder to nod off.
Waking up overheated at night can be due to many factors such as warm bedding or clothes, hot flashes, certain medications, or in some cases, a medical condition. People maintain a fairly consistent body temperature during the day which drops at night by around 1.8 degrees Fahrenheit.
It can make it harder to stay asleep, too. Some studies suggest that the discomfort of sleeping in a hot room can cause more frequent awakenings throughout the night and can disrupt restorative rapid eye movement (REM) sleep.
Hormone levels are a major factor in body temperature, and imbalances in your hormones can cause an elevated body temperature. Many women experience night sweats due to fluctuations in estrogen and progesterone levels, and women going through menopause may be especially prone to night sweats and hot flashes.
Seniors sleep better when their room temperature stays between 70°F and 74°F. Poor sleep can lead to health issues, including memory problems and an increased risk of falls. Temperature control is just one part of creating a good sleep environment.
Does Being Cold Make You Sick? Cold weather and frigid temperatures themselves do not manifest common colds or the flu. But physically being cold, physiologically, might contribute to a weakened immune system, therefore making your body more susceptible to viruses and airborne illnesses.
While fans cannot lower the temperature in a room, they can create a breeze that can help cool you. As the Energy Department points out, fans “cool people, not rooms” through the wind chill effect, in which wind displaces warmer air and helps evaporate sweat from the skin, making people feel cooler.
Depending on one's age and individual needs, the National Sleep Foundation (USA) states that adults need seven to nine hours of good quality sleep per night to remain healthy and alert. School-age children require between nine and eleven hours, while older adults may need only seven to eight.
In his piece, he revealed that through his years of research, he's found that rumination is the biggest thing that causes poor sleep. He says that being worried about something at night has affected his own ability to fall asleep.