What is it called when you have morning wood and roll over?

It's called "TIME TO WAKE UP AND GO TO THE BATHROOM!" :D

According to the health websites I had to reference, morning wood can be from the bladder becoming very full and pressing on the prostate. I'm more under the impression that it's from REM sleep making the body aroused... but, either way, if you roll over on it, you're most likely going to wake up.