Male, 27: I have the same problem (have had it for years now) and find that nutrition changes help most. I start taking a one-a-day multiple vitamin and omega 3 fatty acids (fish oils) twice a day and that helps a LOT. Some moisturizers help too. Good luck- it is really aweful, it drives me crazy but give it two weeks of the above and I think you will notice a difference.
I itch all over when I'm laying down. From my head to my feet. If I have on shorts at night then mostly on my legs. If I have on pants then it's mostly in my croch area.
I have this problem as well. Although I have itchy rashes (Tinea Corporis) etc. that trigger this.
Your problem sounds like some kind of an allergy, where do you specifically itch?