- Up to 85% of the adult population have reported experiencing distressing dreams.
- New research has found people who experience bad dreams in middle age are at higher risk of cognitive decline.
- The work also found that people who experience regular bad dreams are twice as likely to develop dementia.
Bad dreams are unpleasant and can be distressing, provoking negative feelings of fear, anxiety, despair, and sadness. According to the Sleep Foundation, if a distressing or bad dream causes you to wake up, it is classed as a nightmare.
Although often associated with childhood, between 50%–85% of adults report having nightmares, and around 5% report experiencing them weekly. If we include bad dreams, these figures are likely to be much higher.
Research has shown that distressing dreams can become more frequent with age and are associated with disturbed sleep and inadequate rest, both of which have been linked to reduced cognitive function and reasoning.
In recent years, researchers have investigated the impact of bad dreams on degenerative diseases associated with cognitive decline. Research has shown people with Parkinson’s disease who experience bad dreams are at a higher risk of cognitive and physical decline.
Now, new research conducted at the University of Birmingham has shown that healthy people who experience bad dreams in middle age are at greater risk of cognitive decline and dementia.
The study led by Dr. Abidemi Otaiku, a clinical fellow in Neurology at the University of Birmingham, is published in The Lancet journal, eClinicalMedicine.
Dr. Maria C. Carrillo, chief science officer at the Alzheimer’s Association, who was not involved in the study, told Medical News Today:
“This is credible research consistent with the idea that sleep disturbances may be a risk factor or warning sign of cognitive decline.”
For the study, the research team recruited two groups of people:
- a middle-aged group of 605 men and women ages 35–64 who were taking part in the Midlife in the United States (MIDUS) study and followed them for an average of nine years
- an older group of 2,269 people over the age of 65 who were recruited from the Study of Osteoporotic Fractures (SOF) and Osteoporotic fractures in Men Study (MrOS) studies and were followed up for an average of five years
All participants completed cognitive tests and questionnaires about the quality of their sleep and distressing dreams.
During the follow-up periods, the participants underwent more cognitive tests to assess their working memory, memory recall, reasoning, processing speed, and fluency.
Cognitive decline, bad dreams, and age
The researchers found people between the ages of 35 and 64 who experienced distressing dreams were four times more likely to experience cognitive decline.
In the older group, bad dreams were linked to an increased risk of dementia.
The team noted that people who experienced weekly bad dreams were twice as likely to be diagnosed with dementia compared to people who didn’t experience distressing dreams.
According to Dr. Otaiku, “a higher frequency of dreams may represent a more advanced stage of neurodegeneration.”
Speaking to MNT, Dr. David A. Merrill, psychiatrist, and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center at Providence Saint John’s Health Center, explained:
“We know that sustained, high quality sleep is an important protective factor promoting healthy brain aging. Nightmares can represent psychological stress but can also be part of physiologically disrupted sleep […] low oxygen and disrupted sleep cycles not only makes recall of bad dreams more likely but also prevents slow wave or deep sleep from happening.”
The team also found that men are more at risk, with older men who experience weekly distressing dreams being five times more likely to develop dementia.
Distressing dreams are more than sleep disturbance
When asked about the study, Dr. Carrillo commented:
“What’s novel here is the researchers looked at distressing dreams, not more physical sleep disturbances and disorders like insomnia or apnea. However, nightmares can disturb sleep in the same way these disorders do by waking people up in the middle of the night.”
“Previous research has pointed to nightmares being indicative of potential changes in the brain that can precede other dementias like Parkinson’s disease.”
— Dr. Maria C. Carrillo
Dr. James Connell, head of Translational Science at Alzheimer’s Research UK, who was not involved in the study, told MNT:
“Nightmares can be distressing for many and there’s been little research worldwide to see whether people who experience nightmares are more likely to develop dementia […] Alzheimer’s Research UK are spearheading a pioneering initiative to look at ways of detecting the earliest signs of disease, including analyzing sleep patterns.”
“Deep sleep is the part of the sleep cycle needed to rest and restore not only the body but the brain, too. It’s the part of the night where the brain’s cleaning crew, called the glymphatic system, is most active,” said Dr. Merrill.
However, there are limitations to the study. For example, the sleep questionnaires didn’t distinguish between bad dreams and nightmares, so the effects of each can’t be explained. The volunteers were mainly white, therefore, the findings may not apply to wider populations. It is also important to recognize that the study has not been peer-reviewed.
Finally, the use of self-reporting by the volunteers means “their sleep-time experiences […] can be prone to inaccuracy,” said Dr. Connell.
Predicting cognitive decline
Nevertheless, this study has demonstrated that distressing dreams can be linked to cognitive decline and dementia risk in healthy adults. This could represent an important step forward in dementia care as there are few risk factors of dementia or cognitive decline identifiable in middle age.
“While more work needs to be done to confirm these links, we believe bad dreams could be a useful way to identify individuals at high risk of developing dementia and put in place strategies to slow down the onset of disease,” said Dr. Otaiku.
Dr. Merrill supports the discussion of dreams in clinical practice.
“Bad dreams can and should be asked about by doctors and used in guiding not only clinical prognosis but also clinical care […] A patient sharing that they’re having recurrent intense negative dreams or nightmares is an invitation to follow-up with further questions. Have they experienced trauma? Are there stressors at home or at work? Addressing the root causes of bad dreams can help alleviate psychological suffering, which promotes healthy aging,” he said.
“Reducing or preventing bad dreams through treating the root causes of the bad dreams could help slow the progression of age-related degenerative brain disorders like Alzheimer’s and related dementias.”
— Dr. David A. Merrill
Dr. Carrillo echoed the importance of sleep, advising:
“Getting good sleep is important for overall health, including the health of our brains. The good news is there are treatments —both drug and non-drug [options]— that can help address sleep disturbances. If you or a loved one is experiencing sleep difficulties, talk to your doctor.”
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