Short sleep, aging brain

These findings, relevant in the context of Singapore's rapidly ageing society, pave the way for future work on sleep loss and its contribution to cognitive decline, including dementia.

Past research has examined the impact of sleep duration on cognitive functions in older adults. Though faster brain ventricle enlargement is a marker for cognitive decline and the development of neurodegenerative diseases such as Alzheimer's, the effects of sleep on this marker have never been measured.

The Duke-NUS study examined the data of 66 older Chinese adults, from the Singapore-Longitudinal Aging Brain Study(1). Participants underwent structural MRI brain scans measuring brain volume and neuropsychological assessments testing cognitive function every two years.

Additionally, their sleep duration was recorded through a questionnaire. Those who slept fewer hours showed evidence of faster ventricle enlargement and decline in cognitive performance.

“Our findings relate short sleep to a marker of brain aging,” said Dr June Lo, the lead author and a Duke-NUS Research Fellow.

“Work done elsewhere suggests that seven hours a day(2) for adults seems to be the sweet spot for optimal performance on computer based cognitive tests. In coming years we hope to determine what's good for cardio-metabolic and long term brain health too,” added Professor Michael Chee, senior author and Director of the Centre for Cognitive Neuroscience at Duke-NUS.

Published in the journal SLEEP, on July 1, 2014, the study is supported by funding from the Biomedical Research Council, Singapore (BMRC 04/1/36/19/372) and the Singapore National Research Foundation under its STaR Investigator Award (STaR/0004/2008) administered by the Singapore Ministry of Health's National Medical Research Council.

1) The Singapore-Longitudinal Aging Brain Study (started in 2005) follows a cohort of healthy adults of Chinese ethnicity aged 55 years and above. This study is one of the few in Asia that tracks the brain structures and cognitive functions of older adults so closely.

2) Data collected by Lumosity, an online brain-training program, suggests that self-reported sleep duration of seven hours is associated with the best cognitive test scores in over 150,000 adults. As of now it is unknown if this amount of sleep is optimum for cardio metabolic and long-term brain health.