I'm so used to being awake till 4am that by 7:30 I'm up again to take kids to school, spent 15 years or so DJ'ing in the evening at clubs, and events plus being a single parent my kids only watch pepper pig, booba and true on Netflix, now I stay up until like 11pm sometimes midnight just to get in some extra design work, gaming or watch series or movies I wanna watch because until they go to sleep my 3 and 4 year old control all that I think is mine, super hyper active 24/7 lol
So min 4hrs sleep is good enough