Science2021globalhigh confidence

The JAMA Neurology study found that sleeping nine hours or more per night was linked to cognitive problems, particularly impaired decision-making.

Notes on verification

Confirmed by the primary JAMA Neurology study (Winer et al., 2021) and multiple independent secondary sources (Medscape, AlzInfo, Harvard Health) consistently describing long sleep duration's association with impaired executive function/decision-making.

Sources