I think it's partly bullshit. I would consider myself a night owl but: On one hand, if i never check myself, I will just stay up to the late hours of the night,

I think it's partly bullshit. I would consider myself a night owl but: On one hand, if i never check myself, I will just stay up to the late hours of the night, which I often feel is attributed to how I grew up, and as such it's psychologically ingrained in me. Otoh, I successfully followed an 11p-6a sleep schedule for months, but I'd never noticed any negative differences in my general day to day energy/etc levels compared to when I would go to bed late. (Maybe better mood bc being up before most ppl is a great feeling?) But really, the biggest difficulty I had with this regimen was to just go to bed on time, and I think this is more to do with habits rather than genetics. But only partly.