Hypersomnia

[marcellethemonkey]

I'm 25 (male), all my life I've required about 13hrs sleep EVERY night (regardless of bed time).  If i actually get the 13hr, i'm not tired the next day but understandably not always possible, for eg. if i “only” get 10hrs i will be VERY tired that day and also get a 'sleep debt' .
Went to bed at 8pm last night and woke at 1pm today as i "only" slept 11hrs the night before. Ive tried ‘forcing’ 8hrs sleep/night and I was a wreck by day 3/4 and slept for nearly 24hrs straight to compensate.
Had blood tests, sleep study showed nil, only hx is kyphoscoliosis. Im certain I dont have depression or other psych problems, but have trialed several antidepressants anyway for some time, all had ZERO impact on the amount of sleep I require.
Thoughts? It is quite annoying, not being able to live the same lifestyle as nearly everyone I know. I simply just sleep more than everyone. Would I benefit from something like Modafinil?  (I know its usually for daytime sleepiness though) Any other ideas? sleep phase disorder or something like that?