In the book "Why We Sleep" the author writes about how some people are naturally night owls and it damages their health to be forced into a morning routine (e.g., waking up early for school).
According to Dr. Walker, about 40 percent of the population are morning people, 30 percent are evening people, and the remainder land somewhere in between. “Night owls are not owls by choice,” he writes. “They are bound to a delayed schedule by unavoidable DNA hard wiring. It is not their conscious fault, but rather their genetic fate.”
https://www.nytimes.com/2018/08/25/style/sleep-problem-late-...
According to Dr. Walker, about 40 percent of the population are morning people, 30 percent are evening people, and the remainder land somewhere in between. “Night owls are not owls by choice,” he writes. “They are bound to a delayed schedule by unavoidable DNA hard wiring. It is not their conscious fault, but rather their genetic fate.”