Vivid dreams, sweating can be indicators of numerous health conditions, please don't panic but seek professional assessment. After some years I have been diagnosed with REM sleep behavior disorder the symptoms being precisely as you describe. I am so damned exhausted during the day I can hardly function now. I am being seen by a neurologist here in N Ireland who suspects that I have Parkinson's disease or something falling under that umbrella as I also have some cognitive decline, movement problems and tremor.
What I am trying to say is not to let this condition go without followup. Previous reply is spot on, it could be medications or something very simple but in hindsight I wish I had sourced medical advice earlier. Try this link.

http://en.wikipedia.org/wiki/Rapid_e...avior_disorder

On a lighter note I save a fortune on pyjamas. LOL

Good Luck