Is it determined the same way as "healthy" weight? Someone told me that for weight, they do it by measuring a large number of people and see who gets sick and who doesn't and correlate that weight.
Then I was in a forum where someone was saying the requirements are different and some can have 6 hours and be okay and some need 9 hours and I been googling for a few hours but can't find out how doctors would determine that, like is there a list of studies where they looked at different ages, men vs women, different personalities, race, etc, and how much sleep they need? I read in a couple of places that women need more sleep but couldn't find the study that proved that. One site mentioned Duke university but no link to the study.