Sleeping too long increases your risk of dementia 2

Sleeping too long increases your risk of dementia

Nine hours of sleep a night increases the risk of dementia

The potential links between sleep time and the development of dementia have long been debated. A recent study finds that, especially with long sleep times, there is a clear association with the risk of dementia – at least in the Hispanic population.

Those who sleep more than nine hours at night are at increased risk for dementia, the University of Miami Miller School's research team found. An association that is quite surprising, especially since short sleep (less than six hours a night) was not associated with a decline in cognitive ability. The results of the study were published in the journal Alzheimer's & Dementia.

Sleeping too long increases your risk of dementia 3
Sleep times greater than nine hours per night increase the risk of dementia. (Image: baranq /

Effects on cognitive abilities studied

According to the researchers, people of Hispanic or Latino background are at higher risk of dementia "than non-Hispanics," which is why the current study specifically targets this population. Professor Alberto R. Ramos, PhD, and his team estimated the data of 16,000 Hispanics in Chicago, Miami, San Diego and New York. 5,247 participants between the ages of 45 and 75 completed the cognitive test at the beginning of the test period and repeated it after seven years. Sleep time, the presence of sleep apnea, daytime fatigue, and sleep disorders were also reported.

Impaired learning and working memory

"Chronic sleep disorders and prolonged sleep appear to be associated with a decline in cognitive function, which may precede the onset of Alzheimer's disease or other dementias," Dr. Ramos collectively provides data evaluation results. Based on the test results, it became clear that sleep stages greater than nine hours per night were associated with a decline in so-called episodic learning and working memory. The execution function and processing speed in the brain of the affected person are clearly impaired.

Sleep time Indicator of cognitive impairment?

Established cognitive impairment may precede the development of dementia or Alzheimer's disease and should therefore be evaluated as an indicator of an increased risk of the disease. Physicians also need to be aware that there is an association between sleep time and cognitive impairment Ramos continues. Sleep time can identify high-risk patients who could benefit from early intervention. Thus, the risk of dementia could be reduced or even completely prevented, said the study leader.

Further studies are needed

According to the research team, the current study results are of particular relevance to the Hispanic population in the US because they are at a significantly higher risk for Alzheimer's than for non-Hispanics. But the findings also have a general significance. In particular, the link between dementia risk and long sleep is only marginally discussed in the professional world. Future research should include quantification of the effect, considering the potential associations with so-called cerebrovascular disease, which could be the cause of a decline in cognitive ability, according to the US research team. (F)


Dipl. Geogr. Fabian Peters


  • Alberto R. Ramosa et al: The decline and the neurocognitive decline in the Latin American community health study / Latinos study; in: Alzheimer & Dementia (Posted on 09/10/2019),
  • University of Miami Miller School of Medicine: A Study of the Treatment of Sleep Disorders and Alzheimer's among Hispanic Americans (Published 09/10/2019),

Important note:
This article contains general information only and should not be used for diagnosis or treatment alone. It cannot replace a doctor's visit.