has anyone done it? what's it like?

I honestly wouldn't sleep in a bra or a binder. I think there are some major health risks in doing so. I never sleep in with anything on my boobs.

I've slept in my binder for up to 3 nights I think. Its not that big of a deal just obviously don't make a habit of it and sleep in it all the time but who would want to.

For a few nights, it won't kill you, as long as you aren't excessively binding. Just make sure that when you get back, you don't wear one for awhile. Your chest will probably hurt, though, as you're putting quite a bit of pressure on it.

did it for a three day trip...so three nights in a binder.  uncomfortable, but do-able.  Just make sure to bring a couple binders, they start to feel pretty dirty after one night.  especially if you're participating in late-night shenanigans similar to mine....

BUT, like FTE said, there are a few risks involved with it. Lung/rib damage is painful. I took a nap in my binder for just a few hours my my ribs hurt for twice the time my nap was.

i sleep in class or rehearsal all the time, i've just never done a full night.

I've slept in mine and it really wasn't anymore painful then binder in day.

Sleeping in a binder isn't too bad. It's obviously not great, but I was fairly comfortable.
Doing it for too long is obviously a health risk though.

I have fallen asleep a multitude of times with my binder on ... especially after sex ... and it hasn't cause me any problems

i'd say it depends on your own comfort-level and concerns.
I myself sleep in it every night, i only take it off when i shower really (even though i wish i didnt have to, i just hate wet clothes)
yeah, probably not the best thing, but it doesnt bother me. its actually more uncomfortable to NOT sleep with it on, but thats me.
like i said, if your not concerned about the 'risks' and its comfortable enough for you, go ahead, if not, than dont.

there are binders i have slept in and felt fine in the morning and there are some that caused me some pain when sleeping in them. i would recommend you use one with velcro on the side, so before going to sleep you can adjust it to fit a little looser and if you have to get up again you can just pull it tighter again.

they usually cause less pressure when you're lying than they do when you're wearing them during the day

I get crap from my girlfriend for sleeping in mine, but yeah I do it. I take it off when I shower and every few nights to sleep topless. It has never caused me any problems. Skin does need air every now and then to stay healthy though.

Well, I have one with velcro, so I just loosened it a lot (I forgot to bring a sports bra to sleep in before I went to my mom's house for the weekend). I wasn't uncomfortable, although it felt a little weird. Just as long as you don't make a habit of binding while sleeping, a few nights shouldn't hurt you.