GetBetter

The sweet spot, according to the data, falls between roughly 6.4 and 7.8 hours per night…

Short sleep and long sleep don’t appear to damage the body the same way. Fewer than 6 hours was linked to cardiovascular disease, type 2 diabetes, high blood pressure, obesity, kidney disease, and psychiatric conditions, including depression and anxiety. More than 8 hours showed a stronger genetic connection to brain-related conditions like major depressive disorder, bipolar disorder, and schizophrenia, and may often signal that something is already going wrong rather than acting as a direct cause.

Here’s the number that puts everything else in perspective. Short sleepers had a 50% higher hazard of death during the study’s follow-up period. Long sleepers had a 40% higher hazard. People sleeping 6 to 8 hours outlived both groups by a significant margin.

Article says this window can vary by sex but then doesn't address it at all. I'm guessing based on other studies that women need more sleep on average?