In depressive stages it is common to sleep alot, but if you are only having depressive stages, it might just be depression.
I sleep a lot when I am in depression. Even normally I require at least 8 hours usually 9 hours for a decent night sleep. Any less than that and I notice it.
I sleep 10 hours at night and usually take a 2 hour nap during the day. Part of it deals with depression and part of it deals with my medication. There are times that I will wake up at 3am and can't go back to sleep and then I definitely have to take a nap during the day to make it through the day.