Usual sleep duration and cognitive function in older adults in Spain

Area of Science:

• Gerontology
• Neuroscience
• Epidemiology

Background:

• Existing research on sleep duration and cognitive function in older adults presents conflicting findings.
• Understanding the relationship between sleep patterns and cognitive health is crucial for aging populations.

Purpose of the Study:

• To investigate the association between self-reported sleep duration and cognitive function in a representative sample of Spanish adults aged 60 and over.
• To identify potential thresholds of sleep duration that may impact cognitive performance in later life.

Main Methods:

• Cross-sectional study involving 3212 non-institutionalized Spanish adults aged 60+.
• Sleep duration self-reported; cognitive function assessed using the Mini-Examen Cognoscitivo (MEC).
• Linear regression analysis adjusted for key confounders to compare MEC scores across sleep duration categories (≤5, 6, 7, 8, 9, 10, ≥11 hours).

Main Results:

• A significant negative trend was observed: cognitive function (MEC scores) progressively worsened with sleep durations from 7 hours up to ≥11 hours (P < 0.001).
• Individuals sleeping ≥11 hours showed significantly lower MEC scores compared to those sleeping 7 hours (mean difference -1.48).
• This cognitive decline associated with very long sleep duration was comparable to the effect of a 10-year increase in age; no association was found for short sleep (<7 hours).

Conclusions:

• Long sleep duration (≥7 hours) is associated with poorer cognitive function in older adults within the general population.
• Short sleep duration (<7 hours) did not show a significant association with cognitive function in this cohort.
• Findings suggest that excessive sleep may be a marker for underlying issues affecting cognitive health in the elderly.