Halogen heaters

Hi, just bought a 400w halogen heater for my shed to put on while i am sat with my bunnies to keep the chill off - mostly for my benenfit. but would it be safe to leave on overnight for the buns?

Not unless it's thermostat controlled. 400W is quite powerful for a shed and I imagine could easily overheat it.

I wouldn't. As said before, it could get too hot for the buns, and unless it is out of reach then a bun could burn themselves or chew through the wire.
I have one which has a 'tip short'......it swiches off if it is tipped over.
Not a good idea to leave it unsupervised though.