“Long but not short sleep duration was associated with poorer global cognition and specific cognitive abilities like memory, visuospatial skills and executive functions,”
said Sudha Seshadri, founding director of the Biggs Institute and senior author of the study. “These associations were stronger in people with depressive symptoms, regardless of antidepressant usage.”
The study highlights how too little and too much sleep can negatively affect brain function, particularly in memory, attention, and decision-making. Experts recommend 7 to 8 hours of sleep per night to protect brain health.
Since depression often overlaps with sleep issues, with 90% of people with depression reporting sleep problems, the researchers wanted to see how depression might influence the sleep-cognition link.
Participants were grouped by their depression status and use of antidepressants. The study found that those who slept longer and had depressive symptoms showed the most cognitive decline. The effect was weaker but still present in people without depression. Interestingly, people who took antidepressants but had no current depressive symptoms didn’t show the same cognitive decline.
“Future longitudinal studies including large-scale, multi-modal approaches are needed to further elucidate the temporal relationship between sleep disturbances and cognitive changes,” the researchers said.
