Stanford researchers uncover secrets in the brains of sleeping seniors

elderly person sleeping
(Credit: Blend Images/

Sometimes scientists discover the best new stuff by disproving their own hypotheses. This seems to be what happened for a group of sleep researchers who recently set out to study sleep in the senior population.

The plan was for the researchers to set up high-tech equipment in the bedrooms of 150 older adults and examine a phenomenon known as slow brain wave activity at the onset of sleep. Slow brain wave activity, which is measured using EEG testing recorded from electrodes placed on the scalp, has long been associated with cognitive impairment in seniors and considered a sign of pathological aging, according to RUTH O’HARA, an associate professor of psychiatry and behavioral sciences.

“We predicted that we would see increased slow wave activity at sleep onset to be associated with cognitive impairment,” O’Hara said. “But we actually found quite the opposite: We found that increased slow wave activity at sleep onset was associated with better cognitive function.”

Results of the study, which were published last week in the journal SLEEP, showed that slow brain wave activity among the study participants at sleep onset was relatively common, that it was not associated with poorer performance in cognition and that instead, those individuals actually had better performance on a simple reading task.

“Slow wave activity so often assumed to be a harbinger of cognitive or other age-associated impairments, may in fact – depending on when this slow wave activity occurs in the sleep cycle – actually be a marker of better cognitive function and even emotional resilience,” said O’Hara, who is senior author of the study. These findings could have important implications for clinicians working in the field of sleep, she said. Sleep interventions aimed at augmenting slow wave sleep at the onset of sleep in the older individual could perhaps benefit sleep and thus daytime functioning as well.

Further results of the long-term study of these same senior participants are still to come, say the researchers, who are encouraged by what appear to be more accurate results from testing by going into the homes of their subjects.

“If you do studies in the hospital EEG lab, the sample can be biased,” explained MAKOTO KAWAI, a Stanford neurologist and first author of the study. “Our study’s strength was going into a community dwelling.”

This post was originally published on the Stanford School of Medicine’s SCOPE blog.