Public Health.

Area of Science:

• Neurology
• Sleep Medicine
• Epidemiology

Background:

• Sleep disturbances are increasingly linked to dementia risk.
• Previous studies often focused on older adults, limiting understanding of early life-stage associations.
• Investigating sleep-dementia links across different age groups is vital for determining causality.

Purpose of the Study:

• To examine how sleep duration, napping, and daytime dozing relate to dementia risk across various adult age groups.
• To determine if the association between sleep patterns and dementia risk differs between midlife and late life.

Main Methods:

• Analysis of UK Biobank data from 410,162 participants without dementia.
• Self-reported sleep variables (duration, napping, dozing) were assessed.
• Cox models evaluated incident all-cause dementia (ACD) associations across four age strata (≤55, 56-60, 61-65, >65), testing for sleep-age interactions.

Main Results:

• Over 13.6 years, 7,592 incident ACD cases were recorded.
• Short (<6 hours) or long (>9 hours) sleep duration was associated with increased ACD risk across all ages, most notably in those ≤55 and 56-60.
• Frequent napping and daytime dozing also showed significant associations with higher dementia risk, particularly in the younger age groups.

Conclusions:

• Sleep duration extremes, frequent napping, and daytime dozing approximately double dementia risk, with heightened risk observed in individuals aged 60 and younger.
• Midlife sleep patterns are critically important for dementia risk.
• Evidence suggests sleep disturbances may precede dementia onset, highlighting the need for early intervention.