Waking up from a nightmare can leave your heart pounding, but the effects may reach far beyond a restless night. Adults who suffer bad dreams every week were almost three times more likely to die before age 75 than people who rarely have them.
This alarming conclusion – which is yet to be peer reviewed – comes from researchers who combined data from four large long-term studies in the US, following more than 4,000 people between the ages of 26 and 74. At the beginning, participants reported how often nightmares disrupted their sleep. Over the next 18 years, the researchers kept track of how many participants died prematurely – 227 in total.
Even after considering common risk factors like age, sex, mental health, smoking and weight, people who had nightmares every week were still found to be nearly three times more likely to die prematurely – about the same risk as heavy smoking.
The team also examined “epigenetic clocks” – chemical marks on DNA that act as biological mileage counters. People haunted by frequent nightmares were biologically older than their birth certificates suggested, across all three clocks used (DunedinPACE, GrimAge and PhenoAge).
The science behind the silent scream
Faster ageing accounted for about 39% of the link between nightmares and early death, implying that whatever is driving the bad dreams is simultaneously driving the body’s cells towards the finish line.
How might a scream you never utter leave a mark on your genome? Nightmares happen during so-called rapid-eye-movement sleep when the brain is highly active but muscles are paralysed. The sudden surge of adrenaline, cortisol and other fight-or-flight chemicals can be as strong as anything experienced while awake. If that alarm bell rings night after night, the stress response may stay partially switched on throughout the day.
Continuous stress takes its toll on the body. It triggers inflammation, raises blood pressure and speeds up the ageing process by wearing down the protective tips of our chromosomes.
On top of that, being jolted awake by nightmares disrupts deep sleep, the crucial time when the body repairs itself and clears out waste at the cellular level. Together, these two effects – constant stress and poor sleep – may be the main reasons the body seems to age faster.
The idea that disturbing dreams foreshadow poor health is not entirely new. Earlier studies have shown that adults tormented by weekly nightmares are more likely to develop dementia and Parkinson’s disease, years before any daytime symptoms appear.
Growing evidence suggests that the brain areas involved in dreaming are also those affected by brain diseases, so frequent nightmares might be an early warning sign of neurological problems.
Nightmares are also surprisingly common. Roughly 5% of adults report at least one each week and another 12.5% experience them monthly.
Because they are both frequent and treatable, the new findings elevate bad dreams from a spooky nuisance to a potential public health target. Cognitive behavioural therapy for insomnia, imagery-rehearsal therapy – where sufferers rewrite the ending of a recurrent nightmare while awake – and simple steps such as keeping bedrooms cool, dark and screen free have all been shown to curb nightmare frequency.
Before jumping to conclusions, there are a few important things to keep in mind. The study used people’s own reports of their dreams, which can make it hard to tell the difference between a typical bad dream and a true nightmare. Also, most of the people in the study were white Americans, so the findings might not apply to everyone.
And biological age was measured only once, so we cannot yet say whether treating nightmares slows the clock. Crucially, the work was presented as a conference abstract and has not yet navigated the gauntlet of peer review.
Despite these limitations, the study has important strengths that make it worth taking seriously. The researchers used multiple groups of participants, followed them for many years and relied on official death records rather than self-reported data. This means we can’t simply dismiss the findings as a statistical fluke.
If other research teams can replicate these results, doctors might start asking patients about their nightmares during routine check-ups – alongside taking blood pressure and checking cholesterol levels.
Therapies that tame frightening dreams are inexpensive, non-invasive and already available. Scaling them could offer a rare chance to add years to life while improving the quality of the hours we spend asleep.
This article is republished from The Conversation under a Creative Commons license. Read the original article.