For many people, sleeping with a fan on is a must—whether it’s to combat hot summer nights or to enjoy the soothing sound. However, while fans aren’t harmful on their own, using them while you sleep can lead to some unexpected side effects. Here are a few reasons to reconsider relying on a fan at night and some alternatives for staying cool.

It dries out your mouth and nasal passages.**
Fans can evaporate moisture from your body, causing dehydration and drying out your mouth and nose. This is especially true in dry climates, where the effects happen more quickly. To counter this, keep a glass of water nearby to stay hydrated.

It can worsen allergies.**
If you suffer from allergies, sleeping with a fan on may make them worse. The fan circulates dust, pollen, and other allergens, which can trigger asthma, dry eyes, and hay fever. If allergies are an issue for you, a fan might not be the best option.

It can cause muscle cramps.**
Temperatures can drop overnight, and direct exposure to cold air from a fan can cause muscle cramps. Alternatively, during extremely hot nights, a fan blowing hot air may raise your core temperature, leading to heat-related problems like nausea.

Instead of a fan, try sleeping with a window open for fresh air or use breathable, lightweight bedding to stay cool naturally. This way, you can avoid the downsides and still get a comfortable night’s sleep.