not being a plant, I'm not sure I can get energy from the sun to live
Long term fasting and feasting can be very hard on organs as well (knew a young man who did this a lot from an eating disorder, he died of a heart attack at 26 caused by stress of binging/fasting on his body...)
However, the sleep thing is interesting. 2 hours isn't enough, you need a full REM cycle to be healthy (and sleep deprivation long term is very very bad for humans). I can attest that getting 3-5 hours of sleep a night does free up time.