Humidity refers to the concentration of water vapor in the air. The level of humidity in your home can influence many aspects of your personal health. Studies have found both excessively high humidity and excessively low humidity can be problematic, albeit for different reasons.
Humidity can also affect sleep. Studies have found that high humidity can interfere with your sleep cycle and important processes that occur during crucial sleep stages. Additionally, humid climates are associated with higher concentrations of allergens that trigger adverse reactions and disrupt sleep for some people. Maintaining healthy humidity levels in your home can make sleeping in your bedroom much more comfortable.
In a healthy adult, sleep cycles consist of four distinct stages. The first two non-rapid eye movement (NREM) stages are considered light sleep. Your body temperature, heartbeat, breathing rate, and brain wave activity will gradually decrease during these stages. The third NREM stage consists of deep – or “slow-wave” – sleep. During this stage, your temperature, heart and breathing rate, and brain wave activity all reach their lowest levels of the cycle. The slow-wave stage is crucial for tissue repair, bone and muscle recovery, and immunohealth.
The fourth stage consists of REM sleep, which is markedly different from the other three. While your body is completely motionless, your breathing rate will elevate, brain wave activity increases again, and your eyes will move rapidly. Dreaming also occurs during REM sleep. This stage is key for memory consolidation.
High humidity can increase wakefulness and reduce the amount of time you spend in both slow-wave NREM and REM sleep. Since both of these stages are crucial for your overall health, sleepers may experience additional issues related to bodily recovery and memory consolidation.
Humidity can also impact sleep in indirect ways. Excessive dampness may aggravate asthma symptoms, and can also lead to bronchitis, respiratory infections, and other breathing problems that can cause sleep disruptions. Allergens that trigger adverse reactions from sleepers are another concern. Mold thrives in humid environments, as do dust mites, small creatures that often dwell in mattresses and box springs. Humidity also causes some people to sweat excessively, which can make lying in bed uncomfortable.
Conversely, exposure to excessively low humidity levels can cause health problems such as dry skin, itchy eyes, and a sore throat. Low humidity has also been linked to respiratory infection.
Relative humidity is the ratio of water vapor in the air to the amount of vapor that can exist in the air at a given temperature. Warm air can hold more vapor, so while warmer climates tend to feel more humid, cooler air often has higher relative humidity.
The best relative humidity for sleeping and other indoor activities has been debated. According to the Environmental Protection Agency, the best indoor relative humidity falls between 30% and 50%, and it should never exceed 60%. Other studies suggest 40% to 60% is a better range. Regardless, 60% seems to be the agreed-upon threshold for indoor humidity.
A humidistat can be handy if you have trouble controlling indoor humidity levels. These wall-mounted devices are connected to the HVAC system in your home. Simply set the humidistat to your desired relative humidity percentage. When this percentage is exceeded, the HVAC system will automatically turn on and reduce the humidity to the prescribed level.
For maximum comfort, you should also ensure the thermostat in your bedroom is at the right setting. Many experts agree the ideal temperature for sleep is 65 degrees Fahrenheit (18.3 degrees Celsius). While this might sound chilly to some, 65 degrees aligns with the natural drop in body temperature that occurs during sleep and prevents you from overheating.
If 65 degrees won’t work for you, the generally accepted temperature range for sleep is 60 to 67 degrees Fahrenheit (15.6 to 19.4 degrees Celsius).
In addition to maintaining moderate relative humidity levels and a comfortable temperature in your bedroom, you can take other measures to sleep soundly on hot, sticky nights. Tips for sleeping in humid climates include: