Anyone who sleeps has had a nightmare at one point or another. But if the frightening dreams are happening frequently, it may be an ominous sign for health.
Adults who reported having nightmares every week had triple the risk of dying prematurely before age 70 compared to people who rarely or never had them, according to research presented at the European Academy of Neurology Congress in June.
The nightmare sufferers also showed faster biological aging.
This was measured by the length of their telomeres — small DNA sequences that serve as indicators of cellular aging — and their “epigenetic clocks,” molecular markers that measure body aging speed, says lead study author Dr. Abidemi Otaiku, a neuroscientist at Imperial College London in the U.K.
Weekly nightmares were a stronger predictor of premature death than smoking, obesity, a poor diet and sedentary lifestyle, he found.
Since nightmares are common, why would the body have a mechanism that's so unhealthy for us?
“It’s a great question — and a deep one. There is still no consensus on why we dream, let alone why we have nightmares,” Otaiku tells TODAY.com.
“There is no universally agreed definition for a nightmare. But a definition that I think is useful is: A highly distressing or disturbing dream.”
A sleeping brain can’t distinguish dreams from reality, so a nightmare can trigger a person’s fight-or-flight response and prolonged spikes of cortisol, a stress hormone linked to faster cellular aging, Otaiku said in a news release announcing the findings.
Nightmares and Health
The physical effects of bad dreams are real: a racing heart, quickened breath and a sweaty body. Some people wake up crying.
“For those who frequently experience nightmares, this cumulative stress may significantly impact the aging process,” Otaiku noted.
“Additionally, nightmares disrupt both sleep quality and duration, impairing the body's essential overnight cellular restoration and repair.”
This toxic combination likely contributes to accelerated aging, he added.
Nightmares can raise anxiety and negatively impact how a person feels during the day, according to the American Psychological Association. They’re also linked with an increased risk of suicide.
The new study, which has not yet been published in a peer-reviewed journal, was based on data from more than 183,000 adults who reported how often they experienced nightmares and were followed for up to 19 years.
More than 2,400 children whose parents kept track of their nightmare frequency were also included in the study. Kids, too, showed faster biological aging if they had weekly bad dreams.
What Causes Nightmares?
Bad dreams can be triggered by traumatic events, stress, medication, too much alcohol, illness and depression, according to the National Library of Medicine.
Eating certain foods before bed — like cheese if a person has lactose intolerance — can also play a role.
The most common nightmare themes include being chased, physical aggression by another person, falling and the death of a loved one, research has found.
People sometimes dream they're drowning or their teeth are falling out.
Nightmares and erotic dreams are essentially universal — everybody’s had them, brain surgeon and neuroscientist Dr. Rahul Jandial told TODAY.
Nightmares that affect kids usually fade with time, and in adults, an occasional nightmare is fine, he noted.
“But if they show up often and they’re persistent and they’re new, I would think of that as a vital sign — sort of like a pain that doesn’t go away,” Jandial said in a TODAY segment that aired in 2024.
“It’s something to discuss with your doctor if you have persistent new onset nightmares.”
It could be a warning sign of a physical disease like Parkinson’s or lupus, he added.
Some scientists believe that although normal dreaming is beneficial — perhaps by helping to regulate emotions or solve problems — nightmares are a dysfunction of this process, so they have no true purpose and are “an aberration,” Otaiku notes.
A different theory is that nightmares work as a sort of virtual world where people can safely practice survival strategies in response to threats like being chased, he adds.
“This could have led to a survival advantage for our ancestors when they were living in environments that were very dangerous and hostile,” Otaiku tells TODAY.com.
“However, the modern world on the whole is far less dangerous. … And it seems possible that for most people, the long-term costs of nightmares outweigh whatever benefit they once had.”
Otaiku says he leans towards this position, though it’s still an open question.
In a previous study, he found a higher frequency of nightmares may predict cognitive decline and dementia in middle aged and older people.
How to Stop Nightmares in Adults
Nightmares can be prevented and treated, experts say.
Otaiku recommends measures such as:
- Avoiding scary movies.
- Maintaining good sleep hygiene, or habits that set up healthy sleep, like avoiding blue light from screens before bedtime, not eating or drinking before sleep, and lowering the temperature in the bedroom.
- Managing stress.
- Seeking treatment for anxiety or depression.
People who still experience frequent nightmares that disrupt their quality of life may benefit from seeing a sleep specialist, he adds. Otaiku believes routine health checks at the doctor's office that include questions about whether a person is having nightmares could do a lot of good.
“Studies have already shown that treating nightmares can improve both sleep quality and mental health,” he says. “It seems likely that treating nightmares could benefit physical health, too.”
Psychological treatments include imagery rehearsal therapy, where patients are taught to re-write the nightmare and practice imagining the new version during the daytime, according to the Society of Behavioral Sleep Medicine.
It can change the direction of a bad dream and make it less macabre, Jandial said.
“That’s fascinating because nightmares come from our imagination and the treatment is also sort of feeding our imagination in a different way,” he added.
