Many people enjoy sleeping with a fan on in Idaho, but could doing so actually be doing more harm than good for you while you rest? It isn't uncommon to have a fan on while sleeping, but doing so could be doing more harm than good to your body. You could have a window unit, a ceiling fan, a still fan, or one that moves throughout the night. Pros and Cons of Sleeping With a Fan on in IdahoWavebreakmedia Ltd Wavebreakmedia Ltd loading...Let's start with the bad. It is best to use a fan that moves and spreads the air throughout the night over a still fan or ceiling fan.