I wake up for work before the sun rises, and by the time I get back home this time of year, its been set for about 2 hours. Work in preparing dinner, errands or chores, and trying to get in 8 hours of sleep, I'm left with maybe 2-3 hours where I don't have to be doing something or going somewhere in a given weekday. Sure, I could have a side project or a hobby in that time, but then my day would be entirely occupied without any flexibility for if something comes up.
All through college I told myself 6 hours of sleep was fine, that I could catch up on the weekends, but now my sleep schedule seems to be wrecked so 8 hours is nonnegotiable until I stop feeling so exhausted all day.