Experts explain that extreme temperatures can make it difficult for the body to regulate essential hormones, which can interfere with sleep. According to the Sleep Foundation, an ideal bedroom temperature ranges from 60°F (15.5°C) to 68°F (20°C), as this helps maintain the body’s natural thermoregulation process and improves sleep quality.
The human body has an internal system that adjusts temperature, allowing it to function properly regardless of external conditions. This system uses sweating to cool down and shivering to generate heat when needed. Blood vessels also play a role—expanding to release heat when the body is too warm and narrowing to conserve warmth when it is too cold.
Temperature regulation is essential for a good night’s sleep. Many people instinctively cover their feet when they feel cold at night or uncover them when they are too warm. These small adjustments help the body maintain a comfortable temperature, making it easier to sleep.
Temperature has long influenced human sleep cycles. Studies on pre-industrial societies reveal that people naturally fall asleep as temperatures drop in the evening and wake up before sunrise when temperatures are at their lowest. The body’s internal temperature follows a similar pattern, gradually decreasing before bedtime and reaching its lowest point during deep sleep. This drop also affects brain temperature.
Although melatonin production is mostly linked to light exposure, sleeping in a cool room has also been found to boost this important sleep hormone. Studies suggest that excessive warmth can disturb slow-wave sleep (SWS) and rapid eye movement (REM) sleep, both of which are crucial for mental and physical well-being. REM sleep is the phase where dreaming occurs, while SWS helps with muscle recovery, brain detoxification, and hormone regulation.
Researchers have found that elevated bedroom temperatures can increase wakefulness, reduce REM sleep, and put added stress on the body. Similarly, humidity can make it harder for the body to cool down, leading to poor sleep. However, if the room is too cold, the body may use more energy to stay warm, which can also disturb sleep.
Many people have experienced the effects of temperature on sleep, particularly in the summer. Women, especially those undergoing hormonal changes such as menopause, tend to be more sensitive to temperature variations. Keeping the bedroom cool can provide numerous benefits, including deeper sleep, faster sleep onset, improved metabolism, and a lower risk of illness.
A cooler room helps lower cortisol, the body’s stress hormone, while increasing melatonin, promoting restful sleep. It also supports weight management by activating brown fat, a special type of fat that helps burn calories. One study found that participants who slept in a 66°F (18.8°C) room for a month nearly doubled their brown fat levels.
In addition, cooler temperatures enhance insulin sensitivity, reducing the likelihood of developing type 2 diabetes. Sleeping in an optimal temperature range also supports brain health, helping the body complete all necessary sleep cycles, which may lower the risk of Alzheimer’s disease.
If air conditioning or heating is unavailable, there are ways to stay cool at night. Taking a warm shower before bed can trigger the body’s cooling response, helping you fall asleep faster. A study analyzing multiple sleep experiments found that warm showers or baths significantly improved sleep quality, making it easier to rest through the night.
