What sleep characteristics predict cognitive decline in the elderly?

BACKGROUND

Sleep is critical for optimal cognitive function, but as we age both cognitive impairment and sleep problems increase. Longitudinal, population-based studies can be used to investigate temporal relationships between sleep and cognition.

METHODS

A total of 2012 cognitively unimpaired individuals 65 years and over were drawn from the MRC Cognitive Function and Ageing Study (CFAS). They answered self-reported measures including: insomnia symptoms and age of onset, night time wakings, snoring, sleep onset latency, napping, daytime sleepiness and duration of night time sleep. Cognition was measured via the Mini-Mental State Examination.

RESULTS

It was found that daytime napping at baseline was associated with a lower risk of cognitive decline at two and 10 years, and that obtaining ≤6.5h of night-time sleep and excessive daytime sleepiness at baseline were associated with an increased risk at 10 years.

CONCLUSIONS

Daytime napping, night-time sleep duration, and excessive daytime sleepiness may be modifiable behaviours open to intervention strategies, or, clinical indicators of future decline in older individuals.