Does the sun make you sleepy?

I am eating better, getting my exercise in and yet I am sleeping a lot more then I used to. I am constantly taking naps and I am wondering if that has to do that I got a job where I work in the sun. The moment I get home from work, I nap for like 3 to 4 hours plus sleeping at night and that has never happened before I got this job. Is the sun completely draining me? I thought the sun produced melanin which was for your skin but also produced energy?