We spend a third of our lives sleeping. And a quarter of our sleep time is spent dreaming. So for the average person alive in 2022, with a life expectancy of about 73, that’s a little over six years of dreaming.
Yet, given the central role that dreams play in our lives, we still know so little about why we dream, how the brain creates dreams, and, more importantly, what the significance of our dreams might be for our health – particularly the health of our brain.
My 2022 research, published in The Lancet eClinical Medicine A study by an American magazine shows that our dreams can reveal a surprising amount of information about the health of our brains.
More specifically, it was found that having frequent bad dreams and nightmares (bad dreams that wake you up) in middle or older age may be associated with an increased risk of developing dementia.
In the study, I analyzed data from three large U.S. studies of health and aging. These included more than 600 people between the ages of 35 and 64, and 2,600 people aged 79 and older.
At the start of the study, all participants were free of dementia. The middle-aged participants were followed for an average of nine years and the older participants for five years.
At the start of the study (2002-2012), participants completed a number of questionnaires, including one asking how often they suffered from bad dreams and nightmares.
I analyzed the data to find out whether participants with a higher frequency of nightmares at the start of the study were more likely to have cognitive decline (a rapid decline in memory and thinking skills over time) and be diagnosed with dementia.
Weekly nightmares
I found that middle-aged participants who had nightmares every week were four times more likely to experience cognitive decline (a precursor to dementia) over the next decade, while older participants were twice as likely to be diagnosed with dementia.
Interestingly, the association between nightmares and future dementia was much stronger in men than in women.
For example, older men who had nightmares every week were five times more likely to develop dementia than older men who reported no nightmares.
In women, however, the increase in risk was only 41 percent. I found a very similar pattern in the middle-aged group.
Overall, these results suggest that frequent nightmares may be one of the earliest signs of dementia, preceded by the development of memory and thinking problems by several years or even decades – especially in men.
It is also possible that regularly having bad dreams and nightmares can be a cause of dementia.
Given the nature of this study, it is not possible to be certain which of these theories is correct (although I suspect it is the former). However, regardless of which theory turns out to be true, the main implication of the study remains the same, namely that having frequent bad dreams and nightmares in middle and old age may be associated with an increased risk of developing dementia later in life.
The good news is that recurring nightmares are treatable. And the first-line medical treatment for nightmares has already been shown to reduce the buildup of abnormal proteins linked to Alzheimer’s disease.
There are also case reports showing that memory and thinking skills improve after treatment of nightmares.
These findings suggest that treating nightmares may help slow cognitive decline and prevent dementia from developing in some people. This will be an important direction to explore in future research.
The next steps for my research include investigating whether nightmares in young people could also be linked to an increased risk of dementia. This could help determine whether nightmares cause dementia, or whether they are simply an early sign in some people.
I also want to investigate whether other dream characteristics, such as how often we remember our dreams and how vivid they are, can also help determine how likely people are to develop dementia in the future.
Not only could the research help shed light on the relationship between dementia and dreams, and offer new avenues for earlier diagnosis – and potentially earlier interventions – it could also shed new light on the nature and function of the 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.
An earlier version of this article was published in September 2022.