Over 46 million people worldwide are living with dementia and this number is expected to almost triple by 2050. In fact in the US alone over 5 million people are currently estimated to have Alzheimer’s disease.

It is no secret that the disease worsens with age and apparently 1 in 3 seniors die with (not of) Alzheimer’s or another form of dementia. However, a new study suggests that people who sleep for prolonged periods may have an increased chance of developing this terrible disease.

The research was led by Dr. Sudha Seshadri, professor of neurology at Boston University School of Medicine (BUSM), and the findings were published in the Neurology Journal.

Researchers examined data from the Framingham Heart Study. The Framingham Heart Study is a study that began in 1948. They enrolled 5,209 men and women aged between 30 and 62 living in the town of Framingham, MA. The original purpose of the study was to identify risk factors for cardiovascular disease.

One of the questions that the participants had to report was how long they usually slept per night. The researchers clinically followed the participants for 10 years to see who developed Alzheimer’s disease and other forms of dementia.

BUSM researchers then examined the data collected on sleep duration and calculated the risk of developing dementia.

The team found that people who sleep regularly for 9 hours or more were twice as likely to suffer with Alzheimer’s than those participants who slept less than 9 hours. The study’s lead author explained that education also seemed to play a significant role in reducing the risk of suffering with Alzheimers.

Dr. Sudha Seshadri stated that “participants without a high school degree who sleep for more than 9 hours each night had six times the risk of developing dementia in 10 years as compared to participants who slept for less. These results suggest that being highly educated may protect against dementia in the presence of long sleep duration.”

The study also found that people who slept longer seemed to have smaller brain volumes.

As the study was only observational the researchers could only suspect that developing dementia due to excessive sleep was a symptom rather than a cause of the neuronal changes that come with dementia. As a consequence, they speculate, reducing sleep duration is not likely to lower the risk of dementia but it could help with future dementia and cognitive impairment detection practices. Co-corresponding author Matthew Pase, Ph.D., who is a fellow in the department of neurology at BUSM and an investigator at the Farmington Heart Study said “self-reported sleep duration may be a useful clinical tool to help predict persons at risk of progressing to clinical dementia within 10 years. Persons reporting long sleep time may warrant assessment and monitoring for problems with thinking and memory.”

The sooner a patient is diagnosed with dementia, the more time they and their families have to plan ahead and make crucial healthcare decisions.

It is believed that in the US alone families will spend over $5,000 yearly on caring for someone with Alzheimer’s, and the national economic burden is estimated at $236 billion.