In general I try to get 8 hours of sleep each night but those 8 hours feel different depending on the hour I wake up. Last night I slept from 21.30 to 5.30 but I feel worse than when I sleep from 12 am to 8 am for example. There must be more to it than 'just sleep 8 hours'
It's not just sleeping a consistent amount but also sleeping at consistent times. Waking up at 5:30 after 8 hours can feel decent if you consistently do it for a bit.