There are several pros and cons to considerTo sleep with a fan on or not? The sweltering conditions can make it extremely difficult to get a good night’s sleep, making the temptation to leave the fan on all night hard to resist. Cons:Dry eyes and airways(Alamy Stock Photo)“Having a fan on all night can make everything very dry,” says Wilson. “Some people find the sound of a fan really relaxing and sleep-inducing. “Some people who are neurodivergent find that fan air is really off-putting and makes them feel really uncomfortable,” says the sleep expert.