Humidity refers to the amount of moisture present in the air. While temperature is often considered the most important factor in sleep comfort, humidity can also influence how warm or cool the body feels during the night.
The human body regulates temperature partly through sweating. When sweat evaporates from the skin, it removes heat and cools the body. The effectiveness of this cooling process depends heavily on the level of humidity in the surrounding environment.
How evaporation cools the body
Sweat glands release moisture onto the skin when body temperature rises. As this moisture evaporates, it removes heat from the surface of the skin.
This evaporation process is one of the body’s primary cooling mechanisms.
For evaporation to occur efficiently, the surrounding air must be able to absorb moisture from the skin.
Why high humidity can feel warmer
When humidity levels are high, the air already contains a large amount of moisture. This reduces the rate at which sweat can evaporate from the skin.
As a result, the body’s cooling mechanism becomes less effective, and the sleeper may feel warmer even if the air temperature has not changed.
The interaction between humidity and bedding
Bedding and mattress materials can also influence how moisture behaves within the sleep environment. If materials trap moisture close to the body, the local humidity around the sleeper may increase.
This can make the sleeping environment feel warmer and more uncomfortable.
Maintaining balanced humidity during sleep
A balanced level of humidity allows sweat to evaporate effectively while maintaining comfort for the sleeper. When evaporation occurs efficiently, the body can regulate temperature more effectively during the night.
References
National Sleep Foundation
Sleep Research Society