(2023-10-31) Improving Deep Sleep May Prevent Dementia, Study Finds

Improving Deep Sleep May Prevent Dementia, Study Finds. As little as 1 per cent reduction in deep sleep per year for people over 60 years of age translates into a 27 per cent increased risk of dementia, according to a Monash study which suggests that enhancing or maintaining deep sleep, also known as slow wave sleep, in older years could stave off dementia. (sleep tracking)

...looked at 346 participants, over 60 years of age, enrolled in the Framingham Heart Study who completed two overnight sleep studies in the time periods 1995 to 1998 and 2001 to 2003, with an average of five years between the two studies... each percentage decrease in deep sleep each year was associated with a 27 per cent increase in the risk of dementia.

Association Between Slow-Wave Sleep Loss and Incident Dementia. Slow-wave sleep (SWS) supports the aging brain in many ways... Aging was associated with SWS loss across repeated overnight sleep studies (mean [SD] change, −0.6 [1.5%] per year; P < .001)....each percentage decrease in SWS per year was associated with a 27% increase in the risk of dementia (hazard ratio, 1.27; 95% CI, 1.06-1.54; P = .01).

Does the percentage of slow-wave sleep decline with aging, and are intra-individual declines associated with dementia risk? Sleep staging scores were determined in 0.5-minute epochs using the Rechtshaffen and Kales method.... The rate of SWS loss accelerated nominally at ≥60 years of age, peaking at 75 to 80 years of age, followed by slowing. In contrast, REM sleep proportion and total sleep duration remained stable.

Dementia Risk Rises When Deep Sleep Falls. "We previously found that individual differences in slow-wave sleep, assessed at one time point, were not associated with risk of dementia," he said. "Results suggested that chronic declines in slow-wave sleep, rather than individual differences at any given time, are important for predicting dementia risk."

The study had several limitations, the researchers acknowledged. Dementia was diagnosed and ascertained through uninterrupted surveillance in the Framingham study, but Alzheimer's disease biomarkers were not available. "As our study is observational, we are unable to determine whether slow-wave sleep loss causes dementia," Pase and co-authors noted. "Although we conducted several analyses to investigate potential bidirectional associations, it is possible that preclinical dementia disrupts the homeostatic mechanisms that regulate slow-wave sleep."