catnao do you find it worse in the winter? you might need more sunlight, so your body recognises day/night. If you spend a lot of time indoors, your body may think there is more night than there is and by real night be all discombobulated.
Think it is a symptom of SAD but not sure, just know a couple of people who can't sleep and its more of a winter problem.
Grizzly .. SAD has s/t to do with it and yes it is worse in winter...than again on a sunny day it happens I do not even realise that is bright outside...uhmm.. have a feeling this is may be called depression though