Why do I feel uncomfortable with sun in my room?

My father died when I was in the 6th grade and ever since my freshmen year at highschool (i am now a freshmen in college) but anyways ever since then I ALWAYS keep heavy curtains and extra quilts on the window. I absolutly cant stand it when a peep of sunlight comes in to my room. I need to believe that i'm not trying to use my fathers death as an excuse to feel this way but its like i try to take thecurtains down but i just feel uncomfortable and sick, it feels like a goal im trying to achieve when I take the curtains down but I really cant stand sunlight.. i also love it when it rains.. and likeif if and when im cleaning my room.. i only open the window if its dark out or shade.. why have i been stuck like this for so long?