Does poor sleep cause dementia?


It makes sense that after a night of poor sleep, we might not be thinking as clearly the following day. But what about engaging in poor sleep habits throughout our lifetime? Could that put us at risk for long-term cognitive impairments, such as dementia?

Even in people who don’t seem to be cognitively impaired, poor sleep seems to correlate with subtle changes in the same brain proteins that are used to diagnose Alzheimer’s disease and other dementias. The question is why.

Possible explanations

There are several explanations, which are not mutually exclusive and could all be true:

  • Sleep is biologically important for reducing or clearing harmful neurodegenerative proteins from our brains. Exciting new studies in mice have suggested that sleep may clean the brain of amyloid beta, a protein linked to Alzheimer’s disease.

  • Poor sleep and poor cognitive function both could be the effects of an unmeasured harmful causal process. For example, they could both be the common late-developing side effects of harmful medications or a manifestation of some sort of illness.
  • Poor sleep could be an early marker for dementia. That means that the early development of poor sleep efficiency isn’t “causing” dementia but rather is just the first sign in a slow-moving cascade that a dementia is about to occur.

Can practicing good sleep hygiene prevent you from “getting” dementia?

At this time, we don’t know the answer, but we do know that undertreated sleep disorders, including common conditions like obstructive sleep apnea (OSA), are often linked to poor daytime cognitive function.

If you notice a decline in your cognitive abilities such as memory, speak with your primary care physician (PCP) about a sleep work-up. Conditions like OSA and some types of insomnia can respond well to non-pharmacological treatments and can result in improved sleep efficiency and improved quality of life.

Getting the opinion of your medical provider is a critical part of such a work-up. It is not uncommon for over-the-counter sleep aids and some prescription sedative medications to also have harmful effects on cognition and the risk of dementia.

More dementia research is needed

While the research has been proven in mice, it’s hard to accurately measure, in real time, the clearance of small proteins in human brains that may link poor sleep to the risk of dementia. In a project funded by the Michigan Alzheimer’s Disease Center (MADC), we are trying to develop new MRI (magnetic resonance imaging) methods to measure the flow of these proteins during MRI testing.

This approach would allow us to define a “brain clearance system” that might link sleep to dementia risk, thereby allowing us to test the effects of potential treatments.

Our study will be up and running in the next couple of months. More information will be available soon on www.UMclinicalstudies.org.

Next steps

Vikas KotagalVikas Kotagal, M.D., M.S., assistant professor of neurology in the University of Michigan Department of Neurology, sees outpatients with movement disorders including Parkinson’s disease, atypical Parkinsonian conditions, tremor and gait impairments. He directs a subspecialty clinic for patients with suspected normal pressure hydrocephalus. He is passionate about issues impacting access to care for patients with neurodegenerative conditions.



The University of Michigan’s multidisciplinary clinical neuroscience team is made up of more than 70 nationally recognized neurologists, neurosurgeons and many other specialists who have led the way in brain, spine and nervous system care for close to 100 years. Today, patients can access services found at only a handful of facilities and may participate in innovative treatments conducted with the latest research. Neurology and Neurosurgery at the University of Michigan Health System have been recognized by U.S. News & World Report numerous times for excellence in patient care.