Mouse caught in a trap!!

This has happened a bunch of times lately. My wireless mighty mouse will lose connection...sometimes in the middle of the night when my iMac is asleep, and it will wake it up. Other times, in the morning I can wake my computer with a click of the mouse but then it just dies. My wireless keyboard is still connected fine but the mouse won't move. And it is my only mouse so I have to power-off my computer. When i restart it the mouse works fine. Any thoughts? Thanks.