Why Do I Have Nightmares? What Studies Show
Why do I have nightmares? What a 13,922-adult survey, a 67-article review and a sleep medicine paper show about causes, insomnia links and what is unknown.
Ayse Tara, BSc in Nursing
10/27/20266 min read
Why do I have nightmares? The studies we found point to a cluster of linked factors rather than one cause: poor sleep, tiredness, low mood, worry, some medicines and heavy drinking. Most of the evidence comes from surveys, which show what goes together, not what causes what.
This article goes through what two large surveys and a systematic review found, what is recommended when nightmares are frequent, and what is still unknown. If you want a calm bedtime option while you read, Hypnagogia-Pass is one. Each finding below comes with its limits.
Key takeaways
A Finnish survey of 13,922 adults tied frequent nightmares to insomnia symptoms (odds ratio 6.90) and exhaustion or fatigue (6.86); it was cross-sectional, so it cannot show cause.
A 2024 review of 67 articles found insomnia and nightmares positively related, and says the two may aggravate each other.
The American Academy of Sleep Medicine puts nightmare disorder at about 4 percent of adults and recommends Imagery Rehearsal Therapy for it.
A 2022 study of three cohorts linked weekly distressing dreams to later cognitive decline and dementia; it was observational and does not show that dreams cause either.
How common nightmares are, and when they count as a disorder
Researchers describe nightmares as inherently distressing and a barrier to restorative sleep. Search interest is high: Google Keyword Planner estimates 10,000 to 100,000 US searches a month for nightmares, and 1,000 to 10,000 each for why do i have nightmares, what causes nightmares, why do i keep having nightmares and how to stop nightmares. These are ranges, not exact counts.
The American Academy of Sleep Medicine position paper (PMID 29852917) puts nightmare disorder, the clinical diagnosis, at about 4 percent of adults. That figure refers to the diagnosis, not to everyone who has had a bad dream. If your evenings are tense as well, our look at what surveys show about sleep anxiety covers that side.
What the Finnish survey found
The largest survey we opened is a 2015 study in the journal Sleep of 13,922 adults aged 25 to 74 from the Finnish general population. They answered two cross-sectional questionnaires, in 2007 and 2012.
The strongest links with frequent nightmares were insomnia symptoms (odds ratio 6.90), exhaustion and fatigue (6.86) and a depression-related negative attitude toward oneself (1.32 per point). Antidepressant or hypnotic use and frequent heavy drinking were also strongly associated.
Two limits matter. Each questionnaire was a snapshot, so the study cannot tell whether poor sleep or nightmares came first. And a link with a medicine does not show that the medicine is the cause, because people who take such medicines differ in other ways. Please do not change any medicine because of a survey; that is a question for the person who prescribes it.
What a UK survey adds: worry and more
A survey of 846 UK adults asked a narrower question. Negative affect, meaning negative emotion linked to stressful events, is generally treated as the main trigger of nightmares, yet many people with high negative affect do not have nightmares. So the researchers looked for other factors.
After adjusting for negative affect, having nightmares was associated with worry, depersonalisation, hallucinatory experiences, paranoia and sleep duration, with odds ratios between 1.25 and 1.45. Nightmare severity was associated with the first four. Alcohol use and physical activity were not associated with nightmares in this sample, which differs from the Finnish survey on alcohol.
The authors state that causal roles still need longitudinal, experimental and treatment studies. Worry is the item closest to a racing mind. If that sounds like your evenings, racing thoughts at night and overthinking before sleep cover that side.
How insomnia and nightmares connect
A 2024 systematic review in Sleep Medicine Reviews pulled together 67 articles on insomnia, nightmares and dreams. Across people with insomnia, people with nightmares, the general population, students, children, older adults and soldiers, measures of insomnia and nightmares were positively related. The pattern also appeared in studies from the COVID period.
The review says the two may aggravate each other: insomnia raises the chance of nightmares, and nightmares can cost sleep. A cycle like that fits the Finnish figures, but cross-sectional data cannot confirm it. If sleep itself is the sticking point tonight, what to do when you cannot sleep right now is a place to start.
What is recommended when nightmares are frequent
The American Academy of Sleep Medicine position paper recommends Imagery Rehearsal Therapy (IRT) for nightmare disorder, including nightmares linked to post-traumatic stress, and lists other treatments as options that may be used. The 2024 review adds that IRT may reduce both nightmare and insomnia symptoms.
These sources concern clinical treatment of nightmares. The abstracts we opened do not mention bedtime audio or video, so nothing here shows that a sound, a video or a routine reduces nightmares. Our posts on sleep hypnosis and cognitive shuffling describe the same kind of gap for other bedtime practices.
Something to try tonight
Hypnagogia is the drifting, half-lit stretch between waking and sleep. Hypnagogia-Pass is our library of 30 videos, more than 2,400 minutes in total, curated by CantSwitchOff to walk you through the hypnagogic pass: a word, then a matching picture, one after another on a dark screen, with no talking and soft background sound. No ads. It is something to try, not a treatment, and it has not been tested on nightmares. You can read why we built Hypnagogia-Pass before you decide.
Your nightmare questions, answered
What causes nightmares?
The studies we opened point to linked factors rather than one cause: insomnia symptoms, exhaustion, low mood, worry, some medicines and heavy drinking. These come from surveys, so they show what goes together, not what causes what. The Finnish survey of 13,922 adults reported the largest odds ratios, for insomnia (6.90) and fatigue (6.86).
Why do you keep getting nightmares?
If nightmares keep coming back, the surveys we opened point to the same cluster: poor sleep, fatigue, worry and low mood. The 2024 review also describes a possible cycle in which insomnia raises the chance of nightmares and nightmares cost sleep. No survey can say which factor is behind your nights. Frequent nightmares are worth raising with a clinician, who can ask about sleep, mood, alcohol and medicines.
How do I stop from having nightmares?
The only treatment named in the sources we opened is Imagery Rehearsal Therapy, which the American Academy of Sleep Medicine recommends for nightmare disorder. The 2024 review adds that it may reduce both nightmare and insomnia symptoms. The abstracts do not show that a bedtime routine, sound or video stops nightmares. If nightmares are frequent or distressing, ask a clinician about IRT.
Can anxiety cause nightmares?
The evidence is indirect, and the abstracts we opened report worry, not an anxiety diagnosis. A survey of 846 UK adults linked worry to having nightmares and to their severity, after adjusting for negative affect. The authors say causal roles need longitudinal and experimental studies. They add that negative affect linked to stressful events is generally treated as the main trigger, but many people with high negative affect have no nightmares. How to turn off your brain to sleep covers the bedtime side of worry.
What do nightmares mean, and are they a warning?
The studies we opened do not treat a single nightmare as a sign of anything. A large survey links frequent nightmares to insomnia, fatigue and low mood. A separate 2022 study in EClinicalMedicine links weekly distressing dreams to later cognitive decline, but that link is observational.
The 2022 study followed 605 middle-aged adults for up to 13 years and 2,600 older adults for up to 7 years. Compared with no distressing dreams, weekly distressing dreams went with about four times the odds of cognitive decline in the middle-aged group (adjusted odds ratio 3.99, with a wide range of 1.07 to 14.85) and about 2.2 times the odds of dementia in the older group. The associations were significant only among men, and dream frequency came from one questionnaire item. It cannot show that dreams cause decline, and it does not diagnose anyone. Weekly distressing dreams that worry you are worth raising with a clinician.
Know someone who's awake right now?
If you have a friend you have recently talked with about trouble sleeping or bad dreams, or someone you think needs this information, send them this article. It brings them what the science says, in plain words.
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If trouble sleeping lasts for weeks, or if racing thoughts come with other symptoms that worry you, please talk with a doctor. This article is general information, not medical advice, and Hypnagogia-Pass has not been tested in a clinical trial.
Why Do I Have Nightmares? What Studies Show
Why do I have nightmares? What a 13,922-adult survey, a 67-article review and a sleep medicine paper show about causes, insomnia links and what is unknown.
