I listened to this JRE podcast about sleep when it came out 6 years ago and started taking it a bit more serious. According to Matt Walker, 7 hours is the absolute minimum for 99.9% of people, but there's a rare gene that allows some people to run on as low as 5 hours.

Run, in this case I think, meaning not suffer from the effects of certain genes expressing or not based on the hours slept.

1:29:11 He starts talking about the numbers.