Health experts note that extreme temperatures can disrupt the body’s ability to regulate hormones, leading to difficulty falling and staying asleep. The Sleep Foundation recommends keeping bedroom temperatures between 60°F (15.5°C) and 68°F (20°C) to support healthy sleep and maintain the body’s natural thermoregulation process.
The body has an internal system that adjusts temperature based on environmental conditions. This process relies on sweating to release heat and shivering to generate warmth. Blood vessels also play a key role by widening to release heat when needed and narrowing to conserve warmth when the body is cold.
This regulation process plays an important role in sleep. Many people naturally cover their feet when feeling cold or uncover them when feeling hot to find a comfortable balance. Small changes like these help maintain an optimal sleeping temperature.
Temperature has always played a role in sleep cycles. Studies on traditional communities reveal that people tend to fall asleep as nighttime temperatures decrease and wake up before sunrise when temperatures are lowest. The body’s temperature follows a similar pattern, gradually dropping before bedtime and reaching its lowest point during deep sleep. Even brain temperature decreases slightly during this phase.
While melatonin is often associated with light exposure, cooler temperatures also help trigger the production of this essential sleep hormone. Research indicates that warm environments can negatively impact both REM and slow-wave sleep (SWS). REM sleep is the stage where the brain is most active and dreams occur, while SWS helps with physical recovery, brain detoxification, and hormone balance. Both sleep stages are vital for overall health.
Scientists have found that even mild increases in bedroom temperature can interfere with sleep by increasing wakefulness and reducing REM sleep. Humidity can also make it harder for the body to cool itself, resulting in disrupted sleep. However, an overly cold environment may force the body to use extra energy to stay warm, which can also negatively affect rest.
Many people have experienced how temperature impacts sleep, especially during summer heat waves. Women, particularly those experiencing hormonal fluctuations, tend to be more sensitive to temperature variations. Keeping the bedroom cool offers several health benefits, including improved sleep quality, faster sleep onset, better weight management, and reduced health risks.
A cool environment helps regulate cortisol, the body’s stress hormone, while increasing melatonin, promoting deeper sleep. Sleeping in a cool room also stimulates brown fat, a type of metabolically active fat that helps burn stored fat. One study found that participants who slept in a 66°F (18.8°C) environment for a month nearly doubled their brown fat levels.
Cooler sleeping conditions can also improve insulin sensitivity, lowering the risk of type 2 diabetes. Additionally, maintaining an optimal sleep temperature helps the body complete all necessary sleep cycles, potentially reducing the risk of Alzheimer’s disease.
For those without air conditioning or heating, there are ways to stay cool at night. One effective method is taking a warm shower before bed, which activates the body’s cooling response. A study reviewing multiple sleep experiments found that warm showers or baths significantly improved sleep quality, making it easier to fall asleep and stay asleep.
