I think men have an easier time letting go. Our brains are just naturally more active. Our left and right brains work together and possibly work to obtain solutions while we are not influcencing the thought process. I frequently wakeup and find I have the solution to a problem I have been pondering for days.
I love those AH HA awakenings. And, yes they frequently happen in the middle of the night. I also find that I sleep deeply for about three hours and than awaken ready to start my day.