The study – published in JAMA Neurology – followed 283 people without dementia who were over 70. The participants answered questions about their sleep habits and underwent several brain scans over a seven year period.
Researchers found that 22 percent of the group reported issues with daytime sleepiness, a common sign of disrupted sleep. As the study progressed, these participants also showed an increase in a compound called beta-amyloid in their brains. The effect of this build up on nerve cells has been observed in Alzheimer’s disease.
Previous studies have suggested that while the brain sleeps it clears away this accumulation of beta-amyloid. This could mean that a disrupted sleep – leading to excessive daytime tiredness – could cause the build up of this harmful compound.
“I would hope that people understand that good sleep habits are important to have a healthy brain, since it can prevent amyloid, which is one of the primary proteins underlying Alzheimer’s disease,” lead author Prashanthi Vemuri told TIME.
The research also highlights that daytime sleepiness could also be an early indicator of the disease.