I think my muses are hibernating

One would think that winter would be the best time to be writing, but it seems to be the time of the year when I get the least work done on my writing. I think it is the longer hours of darkness in the winter time, I just want to curl up and sleep rather than work. In the summer I can get a bunch of work done on my writing, but I'm not sure how with everything else that I have to get done in the summer time. I guess it just comes down to the longer daylight hours in the summer making me stay awake easier, and the cold dark of the winter making me want to hibernate.