Swollen left eye

For the past year my left has been occasionally swollen and I'm not sure why. I don't have a history of allergy or sinus problems. I can tell when my left will be swollen because I usually get a real nasty headache and the swelling would follow the next morning when I wake up.I don't sleep very well and very rarely get 7 hours of sleep, an average sleep time for me is about 5 1/2 hours. Does this have any thing to do with the swelling of my left eye? There is no redness of the eye and it's not watery but I do feel a painful pressure behind my left eye occasionally when it's swollen and even sometimes when it's not swollen.