https://www.nhlbi.nih.gov/health/sleep/how-much-sleep
Absolutely nothing wrong with sleeping between 8 and 9 hours, you're actually exactly in the healthy range.
I have the same profile : no caffeine or other stimulants, good volume of physical activity; I don't need any reminder to go to bed, I get the obvious the call by being quite tired.
Discussing sleep with people, I found two types that are dominants:
- people who heard "between 7 and 9 hours" and remember "8 hours" (can't say they're wrong here!) - people who heard "between 7 and 9 hours" and remember "the goal is 7 hours", and actually sleep between 5 and 7 hours
> The study concludes that while individuals may initially sleep more when given extended opportunities—likely to recover from prior sleep deprivation—they do not sustain excessive sleep beyond their physiological needs. Consistently sleeping more than 10 hours may indicate underlying health issues and warrants further investigation.
So more than 10 hours might indicate a problem, not 8-9 hours. Also, it's different if people work out a lot or have a physically demanding job:
> For athletes or individuals with high physical demands, 10 hours of sleep might not indicate an underlying health issue but rather an increased physiological requirement. Research has shown that elite athletes often sleep longer than the general population. (this is not from the paper but from a quick search)