The answer Steve is that we all sleep for differing times, depending on what we need.
Sleeping a very long time is a classic depression coping strategy especially if you are sleeping into a lot of the day.
Try not to worry too much, its not a symptom of anything severe but if you are concerned, perhaps when you next see your Dr you could bring the point up
I don't know if you are low carbing or not but for me after about a month of getting serious about carb limiting - I found that I was full of energy and because my bg was fairly stable, so was my mood (at least all my family thinks so :lol: )
Gilly x