My crown attached to a bridge came off. What to do while sleeping? Wearing it now.

I would recommend taking the bridge out while sleeping, so that you do not ingest or inhale the bridge.  If the crown broke off from the bridge, I would recommend contacting your dentist to discuss having the bridge replaced.  Replacing the bridge will prevent your teeth from shifting and allow you virtually no noticeable difference.  Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMDReal Self 100

It sounds like you need to get to a dentist right away and have the bridge evaluated and potentially replaced.  I would not wear it at night while you sleep if it is loose.  Good luck.