Scientists say excessive daytime sleepiness may be an indication that an older person has the Alzheimer’s disease.
According to the scientists, the constant need to sleep during the day may be as a result of accumulated deposits of a brain protein called beta-amyloid.
The deposits are chemically sticky and can go on to form plaques that disrupt communication between brain cells.
Researchers from the Mayo Clinic in the US looked at 283 dementia-free people aged 70 and over who were part of the clinic’s study into ageing. Of these, 72.1 percent were men and 27.9 percent were women.
Participants were asked to complete questionnaires about their sleeping habits when they first joined the investigation.
They also underwent two specialist scans that can detect the presence of beta-amyloid proteins at an early stage of development.
Out of the participants, 22.3 percent reported excessive daytime sleepiness.
This was associated with increased deposits of beta-amyloid proteins in susceptible areas of the brain, the scientists report.
However, they say that the observational nature of their investigation means they cannot prove cause and effect.
The study has been published in the journal JAMA Neurology.