Head Numbness Type Thing

since the age of roughly 16, ive had this kind of dullness to the head, almost heavy headed. over the years (im 18 now) it has got worse. when i sleep i dont wake up feeling refreshed, but basically the same as before i go to sleep, just without the urge to sleep. i get the feeling that i need to wake up

It sometimes makes thinking and general day to day activities strenuous. some things such as hangovers and colds/flu increase the "numbness".

I havnt been to the doctors about it yet, but im tempted to now as im off to uni soon.

any advice on what it may be or things to try?