Is Sleep Duration good for longevity?

Yes — the evidence for this is strong. Sleep duration and mortality risk is one of the more extensively meta-analyzed relationships in sleep research, with multiple independent meta-analyses of prospective cohorts consistently finding a U-shaped relationship: both short and long habitual sleep are associated with higher all-cause and cardiovascular mortality compared to moderate durations. That's reflected in an evidence score of 81/100 for its role in longevity, drawn from 7 studies, with an estimated impact on longevity rated substantial (83/100).