We spend a third of our lives sleeping. And we spend a quarter of our sleep dreaming. So for the average person living in 2022, with a life expectancy of around 73, that means just over six years of dreaming.
However, given the central role that dreaming plays in our lives, we still know so little about why we dream, how the brain creates dreams, and importantly, the importance of our dreams to our health – especially the health of our brains.
My recent study, published in The Lancet’s EClinical Medicine The journal shows that our dreams can reveal a surprising amount of information about the health of our brain.
More specifically, it shows that frequent bad dreams and nightmares (bad dreams that cause you to wake up) in middle or old age may be associated with an increased risk of developing dementia.
In this study, I looked at data from three large US studies on health and aging. Among them there were over 600 people aged 35 to 64 and 2600 people aged 79 and older.
All participants were dementia-free at baseline and followed for an average of nine years for the middle-aged group and five years for the older participants.
At the start of the study (2002-2012), participants completed a series of questionnaires, including one questioning how often they experienced bad dreams and nightmares.
I analyzed the data to find out if participants with a higher frequency of nightmares at baseline were more likely to experience cognitive decline (rapid decline in memory and thinking skills over time) and were diagnosed with dementia.
I found that middle-aged participants who experienced 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 link between nightmares and future dementia was much stronger for men than for women.
For example, older men who had nightmares every week were five times more likely to develop dementia than older men who did not report bad dreams.
However, in women, the increase in risk was only 41%. I found a very similar pattern in the middle-aged group.
Overall, these results suggest that frequent nightmares may be one of the earliest symptoms of dementia, which can precede the development of memory and thinking problems by several years or even decades – especially in men.
Alternatively, it is also possible that regular nightmares and nightmares may even be the cause of dementia.
Given the nature of this study, it is not possible to be sure which of these theories is correct (though I suspect it is the first). Regardless of which theory turns out to be true, however, the main implication of the study remains the same, meaning that regular 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. First-line treatment of nightmares has been shown to reduce the build-up of the abnormal proteins associated with Alzheimer’s disease.
There have also been reports of cases showing improvements in memory and thinking skills after treating nightmares.
These findings suggest that treating nightmares may help slow cognitive decline and prevent the development of dementia in some people. This will be an important avenue to investigate in future research.
The next steps in my research will include finding out if nightmares in young people could also be linked to an increased risk of dementia. This can help determine if nightmares are causing dementia or are simply an early symptom in some people.
I also plan to investigate whether other dream characteristics, such as how often we remember our dreams and how vivid they are, could also help determine how likely people are to develop dementia in the future.
Not only can this research help shed light on the link between dementia and sleep and provide new opportunities for earlier diagnoses – and perhaps earlier interventions – but it can also shed new light on the nature and function of the mysterious phenomenon we call sleep. .
Abidemi Otaiku, NIHR Academic Clinical Fellow in Neurology, University of Birmingham
This article has been republished from The Conversation under a Creative Commons license. Read the original article.