Doctor and Academic of the University of Birmingham (Great Britain) specialized in Neurology.
We spend a third of our lives sleeping. And a quarter of the time we sleep is spent dreaming. So for someone with a life expectancy of about 73 years, that’s a little over six years of sleep.
However, considering the central role that sleep plays in our lives, we still know very little about why we dream, how the brain creates dreams and, more importantly, how important our dreams can be for our health. Especially the health of our brain. We spend a third of our lives sleeping. And a quarter of the time we sleep is spent dreaming. So for someone with a life expectancy of about 73 years, that’s a little over six years of sleep.
My latest study, published in the journal eClinicalMedicine de The Lancet, shows that dreams can reveal a surprising amount of information about the health of our brain. More specifically, it suggests that having bad dreams and frequent nightmares (bad dreams that make you wake up) during middle or old age, may be linked to an increased risk of developing dementia.
In the study, I analyzed data from three large US studies on health and aging. More than 600 people between the ages of 35 and 64 participated, and 2,600 people aged 79 and over.
All participants were free of dementia at the start of the study and were followed for an average of nine years for the middle-aged group and five years for the oldest participants.
At the beginning of the study (2002-2012), The participants completed a series of questionnaires, including one that asked about how often they experienced bad dreams and nightmares.
I analyzed the data to find out if participants with a higher frequency of 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.
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. For their part, older participants were twice as likely to be diagnosed with dementia.
Curiously, the connection 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 compared to older men who did not have nightmares. In women, however, the increased risk was only 41%. A very similar pattern was found in the middle-aged group.
Symptom or cause of dementia?
Overall, these results suggest that frequent nightmares may be one of the early signs of dementia, which can precede the development of memory problems and thinking skills by several years or even decades, especially in men. On the other hand, it is not unreasonable to suspect that having bad dreams and nightmares regularly is even a cause of dementia.
Given the nature of this study, it is not possible to be sure which of these theories is correct (although I suspect that it is the first). Regardless of which theory turns out to be true, however, the main implication of the study remains the same, namely that having bad dreams and nightmares on a regular basis in middle and old age may be somehow related to an increased risk of develop dementia as they age.
Recurring nightmares can be treated
The good news is that recurring nightmares are treatable. And first-line medical treatment for nightmares has already been shown to decrease the buildup of abnormal proteins associated with Alzheimer disease. There have also been case reports showing improvements in memory and thinking skills after treating nightmares.
These findings suggest that treating nightmares could help slow cognitive decline and prevent the development of dementia in some people. This will be an important avenue to explore in future research.
The next steps in my research will include the study of whether nightmares in young people may also be related to an increased risk of dementia. This could help determine if nightmares are the cause of dementia or just an early sign in some people.
I also plan to investigate whether other characteristics of dreams, such as how often we remember them and their intensity, can help determine how likely people are to develop dementia in the future.
This research could not only help clarify the relationship between dementia and sleep, and provide new opportunities for earlier diagnosis – and possibly earlier intervention. It could also shed new light on the nature and function of the mysterious phenomenon we call sleep.
This article has been published in The Conversation.