High Temperatures in Bedroom Reduce Sleep Quality by 5–10%

High Temperatures in Bedroom Reduce Sleep Quality by 5–10% — Study

15 November , 2026

According to Experts Club, elevated air temperatures in the bedroom can significantly impair the quality of nighttime rest, increase wakefulness, and reduce the duration of deep sleep. When the room temperature rises from 25 to 30 degrees Celsius, sleep efficiency in older adults decreases by 5–10%, according to the results of a scientific study published in the journal *Science of The Total Environment*.
Scientists studied the effect of bedroom temperature on the duration, quality, and restlessness of sleep among older adults living in their own homes. The study included 50 participants with an average age of about 79 years. The observations lasted 18 months. The researchers used portable sleep monitors and environmental sensors to measure air temperature and humidity.
The results showed that participants experienced the most restful and effective sleep at air temperatures between 20 and 25 degrees. When the temperature rose to 30 degrees, sleep efficiency decreased by 5–10%.
At the same time, the researchers identified significant individual differences, so the temperature values obtained cannot be considered a universal standard for people of any age.
An additional experimental study, published in the journal *Building and Environment*, also demonstrated the negative impact of high temperatures on the sleep of older adults.
During the experiment, raising the bedroom temperature from 27 to 30 degrees resulted in a 26.3-minute reduction in total sleep duration. Sleep efficiency decreased by 5.5%, the duration of rapid eye movement (REM) sleep decreased by 5.3 minutes, and nighttime wakefulness increased by 27 minutes.
The researchers also found that improved ventilation led to an increase in deep sleep duration by 10.3 minutes and in REM sleep duration by 3.7 minutes.
Experts attribute the effect of temperature to the body’s thermoregulatory mechanisms. Before falling asleep, the body’s core temperature naturally begins to drop. To achieve this, the body redistributes heat to the skin’s surface and releases it into the environment.
If the air temperature is too high, the cooling process becomes more difficult. This can delay the onset of sleep, disrupt the sleep cycle, and increase the number of nighttime awakenings.
According to the scientific review “Thermoregulation in Sleep Disorders,” published on April 12, 2026, in the Journal of Clinical Medicine, disruptions to the natural drop in body temperature are associated with sleep fragmentation and the onset of daytime symptoms, including fatigue and reduced alertness.
Poor-quality sleep can negatively affect concentration, memory, emotional stability, and work performance the following day. At the same time, the severity of these effects depends on the duration and severity of the sleep disturbance, the person’s age, and other factors.
A separate problem during the heating season is the decrease in relative humidity indoors.
Heating cold outdoor air without additional humidification leads to a decrease in its relative humidity. Dry air can cause discomfort in the nose and throat, as well as dryness of the mucous membranes and skin. For some people, this can exacerbate nasal congestion and further interfere with restful sleep.
The U.S. Environmental Protection Agency (EPA) recommends monitoring indoor humidity and ensuring it does not exceed 50% when using household humidifiers. Excessive humidity can promote the growth of mold and other biological contaminants.
According to the Sleep Foundation’s recommendations, for many adults, a comfortable bedroom temperature falls within the range of 16–20 degrees Celsius. However, choosing the optimal setting depends on individual characteristics, age, sleepwear, and the blankets used.
In particular, studies of older adults suggest that in some cases, higher temperatures—around 20–25 degrees—may be most beneficial.
To improve sleep conditions, experts recommend avoiding overheating the bedroom, regularly ventilating the room, using seasonally appropriate bedding, and controlling humidity levels.