According to Mark Reddick, writing on The Sleep Advisor, fans can set off allergies and are not good for those with asthma as they move dust around the room.
He said: "For some people, having a ceiling or floor fan in the room helps them fall asleep and stay cool during the night as the fan moves dust around the room.
"For others, it can keep them awake, trigger asthma attacks or dry out their eyes.
"As a fan moves air around the room, it causes flurries of dust and pollen to make their way into your sinuses. If you're prone to allergies, asthma, and hay fever, this could stir up a whole lot of trouble.