According to experts, the body struggles to regulate hormones when exposed to extreme heat or cold, making it harder to fall and stay asleep. The Sleep Foundation suggests that an ideal bedroom temperature falls between 60°F (15.5°C) and 68°F (20°C), as this helps maintain proper body temperature regulation and promotes high-quality sleep.
The human body has an internal system that manages temperature, allowing it to adjust regardless of the surrounding climate. This system works through various physiological responses like sweating, shivering, and changes in blood flow. Sweating helps release heat by evaporating moisture, while shivering generates warmth by causing muscles to contract rapidly. Blood vessels also play a role—when the body needs to cool down, they expand to allow more heat to escape. Conversely, they narrow to conserve warmth when the body is cold.
This temperature regulation becomes noticeable during sleep. Many people instinctively cover their feet when they feel cold at night or uncover them when feeling too warm. These small adjustments help regulate body temperature and improve sleep comfort.
Temperature has long influenced human sleep patterns. Researchers studying pre-industrial societies found that people naturally fall asleep as temperatures drop in the evening and tend to wake up before sunrise when temperatures are lowest. Body temperature also follows a natural cycle, dropping about two hours before sleep and reaching its lowest point during deep sleep. This cooling effect even extends to brain temperature.
While melatonin production is mostly associated with light exposure, cooler temperatures also contribute to its release. Studies indicate that excessive warmth can disrupt both slow-wave sleep (SWS) and REM sleep, two essential sleep stages. REM sleep is the phase where dreaming occurs and brain activity peaks, while SWS supports muscle recovery, waste removal from the brain, and hormone release. Both stages are necessary for overall well-being.
Research has shown that elevated bedroom temperatures increase alertness at night, shorten REM sleep, and place added strain on the body. Similarly, humidity can also impact sleep by reducing the body’s ability to cool down, leading to increased wakefulness. However, if the room is too cold, the body may use extra energy to stay warm, which can also disturb sleep.
Many people have experienced how room temperature affects sleep, particularly during summer heat waves. Women, especially those going through hormonal changes like menopause, are even more sensitive to temperature fluctuations. Sleeping in a cool room offers several health benefits, including improved sleep quality, faster sleep onset, better weight management, and a reduced risk of illness.
Cooler temperatures help lower stress hormone levels while boosting melatonin production, ensuring restful sleep. They also aid in weight management by activating brown fat, a metabolically active tissue that helps burn stored fat. One study found that sleeping in a 66°F (18.8°C) environment for a month nearly doubled participants’ brown fat levels.
Furthermore, cooler sleep environments enhance insulin sensitivity, potentially lowering the risk of type 2 diabetes. Sleeping in an optimal temperature range also supports brain health by allowing the body to complete all necessary sleep cycles, potentially reducing the risk of Alzheimer’s disease.
Even without heating or air conditioning, there are ways to stay cool at night. Taking a warm shower before bed can help, as it triggers the body’s cooling response. A meta-analysis of sleep studies found that warm showers or baths before bedtime improved sleep quality and efficiency, supporting a more restful night’s sleep.
