All articles · Temperature & sleep
What is the best bedroom temperature for sleep?
Why temperature affects sleep
Sleep is closely connected to thermoregulation. Across the evening and night, core body temperature follows a circadian rhythm while heat is redistributed toward the skin. Excess environmental heat can interfere with this process and increase wakefulness or destabilize sleep.
A 2024 systematic review found that higher indoor or outdoor temperatures are generally associated with poorer sleep quantity and quality, especially during the hottest periods. Review.
Why Sleeple does not prescribe one number
A single recommendation such as 18°C is easy to remember but oversimplifies the system. Thermal comfort in bed depends on duvet insulation, mattress, clothing, humidity and airflow. The same room can feel comfortable with light bedding and excessively warm with a heavy duvet.
A review of thermal environment and sleep highlights that heat and cold effects depend strongly on bedding and clothing. Review.
A practical adjustment method
- Track approximate room temperature for several nights.
- Keep bedding stable at first.
- If you are too warm, reduce insulation before making the room dramatically colder.
- Add airflow through ventilation or a fan when appropriate.
- Use air conditioning when needed during very hot nights, without overcooling the room.
The bed microclimate matters
Your body experiences more than room air. Bedding creates a local thermal and moisture environment. Research on sleep environments highlights the importance of the thermal properties of sleepwear and bedding. Review.
Humidity changes how heat feels
High humidity can reduce evaporative cooling and make moderate heat feel much worse. Thermal comfort therefore depends on more than temperature alone.
The Sleeple rule
Start somewhat cool rather than warm, then adjust bedding and airflow according to comfort. If you regularly wake drenched in sweat despite a reasonable bedroom environment, do not assume room temperature is the only cause; persistent night sweats can have medical causes worth discussing with a clinician.