i dunno. even when i was younger a had no responsiblities and no sleep debt (say summer) i would always sleep at least 10 hours a day. i get sick like once every 4 years. my mom is the same though needs 10 hours of sleep a night. and my dad too although not so much. maybe its hereditary. but it is very annoying, i always feel like im missing out on awake life. 2 hours a day of extra sleep compared to everyone else adds up quick. i can and do get by on 6 - 8 hours per night, but i have to make up for it every few days by going to sleep early/waking up late to get some 12 hour sleep days.