As I grow older, I find the opposite - if I haven't had a physically exhausting day, I need only 6 hours, else max 8 hours. Anything more than this has a negative impact on my mood and health.
That is true for me, too. I used to sleep 9 hours a day when I was in my early 20s, now I cant imagine anything more than 7 hours.
Do either of you do physical exercise or weightlifting?
I used to, not any more in the last 5 years or so. Have to start again - feel quality of sleep was better when I used to exercise.
I hate articles like these. I sleep 6-7 hours, and it works all right for me. When I sleep 8+ hours, I feel a bit more fresh, but that doesn't really help me do anything more in my day. Id rather have the extra hour to duck around on Reddit or (ideally) do something productive.
It also feels a bit icky that this scientist wanted his app to be plugged into the article...
you can't generalise sleep, many people need much more or some people need much less, just see what works for you