Grew up in a structured household. 7a, 11:30a, 6p meals. Mom always wondered why I wasn't hungry... Also worked last 20yrs, before disability, 7a-7p and never got used to it.
Tried all that sleep hygiene stuff, didn't work for me.
I sleep when sleepy but that's only with meds. & eat when hungry, don't eat between meals.
My body clock is what it is & I don't worry about it.
Also don't work a job & that helps!