What sleeping with a fan on does to your body—and how to sleep cooler safely

Doctors say a nighttime fan can help cool you, but concentrated airflow can trigger allergies or asthma, clog sinuses, dry skin, and stiff neck. To reduce risks, use oscillation or aim the breeze away from you, keep the fan and room clean, maintain humidity around 30-50%, and consider saline nasal spray if nasal passages dry. The fan doesn’t cool air, it moves it across your skin to help sweat evaporate, and long-term damage is unlikely.