Battery operated fan quesiton ?

I have a couple of those USB charged fans with batteries. I'm very impressed so far. One is clip on, one is mounted on a tripod with twisty/grippy legs. Both of them can run straight from USB power as long as it's a 2 amp supply, and both claim an 8 hour run time. One of them is permanently mounted on my home bed providing just what you're asking for. One of the best fans I've ever purchased. More recently I added that one mounted on the tripod. I've been using it in battery mode for over a week to provide ventilation while I'm working out on an exercise machine. So far it still claims to be fully charged, and I've been using it on the medium setting.

I think one of those higher capacity phone charging battery units would easily keep a couple of these charged up, allowing you to enjoy a good night's sleep.