RECENT research conducted in the USA suggests that there may be a link between sleep duration and brain volume. Kevin González, Department of Neurosciences and Shiley-Marcos Alzheimer’s Disease Research Centre, University of California San Diego School of Medicine, California, USA, and colleagues, found that longer sleep duration was associated with lower total brain and grey matter volume in a study of Hispanic and Latino individuals.
Researchers used data from the SOL-INCA MRI study in order to analyse 2,334 Hispanic participants, aged 35–85 years, who had undergone neuroimaging, cognitive testing, and who had self-reported their daily sleep duration. Primary outcomes included total and regional brain volumes, which were categorised by number of hours slept per night (fewer than 6 hours, 6–9 hours, and more than 9 hours). Continuous age at time of MRI, length of time between MRI visits, sex, education level, ethnic background, and continuous BMI were the covariates considered.
The findings showed that the majority of participants (79%) slept between 6–9 hours, and that increased sleep was associated with a smaller brain volume (β total brain=0.05). This was consistently true for participants aged 50 years and older after adjusting for mild cognitive impairment status. It was found that those who slept for over 9 hours had smaller grey and occipital grey matter volumes (β combined grey= 0.17; β occipital grey=0.18) when compared to the group that slept 6–9 hours.
González and colleagues concluded that sleep duration is an important factor in brain ageing, as well as cognitive impairments and physical health. The team added that “sleep studies are particularly important for Hispanics, who have up to four times the risk for Alzheimer’s disease and related dementias, compared with non-Hispanic Whites.”
