Some people can’t sleep without their fan on. Whether it’s because of hot summer nights or because the sound helps them to fall asleep, the wind blowing directly at them is a necessity. But although the fan itself is not a toxic object, using it at night can lead to certain consequences. We have some simple solutions for how you can have cooler nights without it. 1. It will dry out your mouth and nasal passages. Studies reveal that leaving the fan on can help evaporate sweat and moisture from your body, leading to dehydration and the drying of the mouth and nasal passages. If you live in a dry area, this needs special attention, since these consequences can appear even faster. In general, however, a cup of water is more than enough to restore the water you need.