I have evaporative cooling, so on warm nights I generally leave the fan on and have the window open to keep the air moving through. The bed fan is nice because it blows air under the covers (which is a very light cotton doona - I can’t sleep uncovered) and it has a remote control, so if I wake up too warm I can turn it on/up without moving. It also helps to remove moisture from the bed so it doesn’t feel quite so sticky.