An anterior-posterior gradient in hippocampal subfield volumes linking sleep health to cognition in young adults.

Sleep plays a critical role in maintaining hippocampal integrity and supporting cognitive function. However, it remains unclear how variations in sleep are associated with the structurally heterogeneous subfields of the hippocampus and how this association relates to cognition in healthy young adults. This study aimed to elucidate the multivariate relationships among sleep duration, quality, and timing, the specific hippocampal subfield volumes, and cognitive functions in a large sample of healthy young adults. We applied multiset canonical correlation analysis to data from 942 young adults (ages 22-37) from the Human Connectome Project. We examined relationships among self-reported sleep parameters (via the Pittsburgh Sleep Quality Index), high-resolution hippocampal subfield volumes, and a broad set of cognitive performance measures. We identified a single significant mode of covariation, wherein better sleep health-characterized by a moderate sleep duration (reflecting a nonlinear, inverted U-shaped relationship), higher sleep quality (e.g., fewer awakenings, less discomfort), and optimal sleep timing-was robustly associated with larger hippocampal volumes, particularly in the anterior subfields. This sleep-hippocampus pattern was also associated with enhanced cognitive performance. Our findings reveal a specific link among sleep, an anterior-dominant pattern of hippocampal structure, and cognition in healthy young adulthood. The anterior hippocampus may serve as a key neural hub through which the cognitive benefits of healthy sleep are manifested early in life.