We spend a third of our lives asleep, and a quarter of that time dreaming, meaning that the average person living in 2022 will have an average life expectancy of 73 years, meaning they will spend just over six years dreaming.
Yet given the central role dreams play in our lives, we still understand very little about why we dream, how the brain generates them, and, importantly, what dreams mean for our health, and in particular the health of our brain.
My research, published in The Lancet eClinical Medicine in 2022, showed that dreams can reveal a surprising amount of information about brain health.
More specifically, the study showed that frequent bad dreams and nightmares (dream episodes that wake you up) in middle age and older age may be associated with an increased risk of developing dementia.
The study analyzed data from three large U.S. studies on health and aging, which included more than 600 people aged 35 to 64 and more than 2,600 people aged 79 or older.
All participants were dementia-free at the start of the study, and the middle-aged group were followed up for an average of nine years, while the older group was followed up for an average of five years.
At the start of the study (2002–2012), participants completed a range of surveys, including a questionnaire asking how often they had bad dreams or nightmares.
I analyzed the data to see whether participants who had more frequent nightmares at the start of the study were more likely to experience cognitive decline (a rapid decline in memory and thinking skills over time) and be diagnosed with dementia.
A weekly nightmare
They found that middle-aged participants who had weekly nightmares were four times more likely to experience cognitive decline (a precursor to dementia) over the following 10 years, and older participants were twice as likely to be diagnosed with dementia.
Interestingly, the association between nightmares and future dementia was much stronger for men than for women.
For example, older men who had weekly nightmares were five times more likely to develop dementia than older men who reported not having nightmares.
For women, however, the increased risk was only 41 percent. A very similar pattern was seen in middle-aged people.
Overall, these results suggest that frequent nightmares may be one of the earliest signs of dementia, and that, particularly in men, nightmares can appear years or even decades before the onset of memory and thinking problems.
Alternatively, regular bad dreams or nightmares could be a contributing factor to dementia.
Due to the nature of this study, we can’t say for sure which theory is correct (although I think it’s the former), but regardless of which theory is correct, the main takeaway from this study remains the same: regularly having bad dreams or nightmares in middle-aged and older adults may be linked to an increased risk of developing dementia later in life.
Fortunately, recurring nightmares are treatable, and the first-line treatment for them has already been shown to reduce the buildup of abnormal proteins associated with Alzheimer’s disease.
There are also case reports of improved memory and thinking after treating nightmares.
These findings suggest that treating nightmares may be able to slow cognitive decline and prevent the onset of dementia in some people — an important avenue to explore in future research.
Next steps in my research include investigating whether nightmares in young people are also associated with increased dementia risk, which could help determine whether nightmares cause dementia or whether for some people nightmares are simply an early symptom.
They also plan to examine whether other dream characteristics, such as how often a person remembers their dreams and how vivid they are, can help predict the likelihood of developing dementia in the future.
This research not only sheds light on the relationship between dementia and dreams and offers new opportunities for earlier diagnosis and even intervention, but may also shed new light on the nature and function of that mysterious phenomenon we call dreaming.
Abidemi Otaiku, NIHR Academic Clinical Fellow in Neurology, University of Birmingham
This article is republished from The Conversation under a Creative Commons license. Read the original article.
A previous version of this article was published in September 2022.
