Sleeping with a fan may seem like a simple way to stay cool on hot nights, but experts warn it has drawbacks. Studies show “a lower body temperature (preferably between 65 and 68°F)” improves sleep, but a fan may cause more harm than good.

Fans circulate dust, pollen, and pet dander, which can “exacerbate allergies” and cause congestion, coughing, or itchy eyes. The moving air can also “dry out your mouth, throat, and nose,” irritating sinuses and increasing mucus. Long-term exposure to a steady breeze may lead to “stiff or sore muscles,” especially in the neck and shoulders.

Skin and eyes can become dry, with symptoms worsening for those with eczema, sensitive eyes, or contact lenses. Noise from a fan may also disturb light sleepers, reducing deep sleep.

A fan “only moves air around,” creating a cooling sensation but not actually lowering the room or body temperature. In extreme heat, it’s far less effective than air conditioning.

Better alternatives include breathable bedding, blackout curtains, staying hydrated, or using cooling mattress pads. The ideal sleep environment balances comfort, temperature, and personal preference without the side effects of overnight fan use.