This translational study investigates how social isolation and circadian disruption interact to affect rest–activity organization in Drosophila melanogaster, a behavioral model relevant to Alzheimer's disease risk. Using a factorial design varying social history (continuous socialization, adult isolation, larval isolation) and light condition (light–dark cycle vs. constant darkness), we found that socially enriched flies under light–dark conditions showed significantly longer, more consolidated rest bouts, while isolated flies in constant darkness exhibited shorter, more fragmented rest. These findings support rest fragmentation as an AD-relevant phenotype linking social isolation, circadian instability, and neurodegenerative risk.

Keywords: social isolation, circadian rhythm, sleep fragmentation, Drosophila, Alzheimer's disease, neurodegeneration.