Sleep apnea and nightmares: can it cause night terrors?

Sleep apnea can play a part in nightmares, and in some adults it can set off night terror-like episodes or movements that look like acting out dreams. The research is made up of small studies, and they don't all agree. The more consistent finding is the hopeful one: when sleep apnea is treated, frightening dreams and night-time episodes often fade.

Can sleep apnea cause nightmares?

Sleep apnea can contribute to nightmares, though it isn't a simple cause-and-effect. A 2019 review in Frontiers in Neurology explains that the repeated breathing pauses, broken sleep and oxygen dips of sleep apnea may trigger parasomnias, the umbrella term for unusual events in sleep, including nightmares. The same review notes that results are contradictory. Some studies found people with sleep apnea dream less, while others found more dreams with emotional, often violent or hostile content.

A 2013 study in Sleep Medicine helps explain the mixed picture. Researchers compared 99 people with sleep apnea who had nightmares to 124 who didn't. Overall sleep apnea severity was similar, but those with nightmares had more breathing events during REM sleep, the stage when most vivid dreaming happens. REM-stage breathing events and broken sleep were the two factors that independently predicted nightmares.

Not every study points the same way. A 2006 study of 323 people with sleep apnea found they actually reported fewer nightmares, which the researchers put down to remembering fewer dreams overall. Measures of how severe the sleep apnea was didn't line up with nightmare frequency. Instead, mental health conditions and psychiatric medicines were linked with more nightmares.

So sleep apnea seems to matter most when it hits REM sleep hard, and other factors such as stress and mental health carry a lot of weight too. Our guide to sleep stages explains what REM sleep is.

Do people with sleep apnea dream about choking or drowning?

People with sleep apnea dream about choking, suffocating or drowning less often than many expect. The 2019 review found that although there are reports of breathing-related dreams, most studies that looked at dream content found these themes were unusual.

What does seem to change is the emotional tone. In a 2006 study in the Journal of Sleep Research, researchers woke 20 people with severe sleep apnea and 17 healthy volunteers during REM sleep and asked about their dreams. People with sleep apnea remembered dreams about as often as the volunteers, but their dreams were longer and more emotional. Violent or highly anxious dreams appeared only in the sleep apnea group before treatment.

Does sleep apnea cause night terrors?

Sleep apnea can trigger night terrors in some adults, though the evidence comes from small studies. The NHS lists sleep apnoea among the conditions that can cause night terrors and nightmares, alongside stress, restless legs syndrome, some medicines and conditions that affect the brain.

Night terrors and nightmares are different events. The NHS says night terrors happen early in the night, can involve screaming, shouting or thrashing with eyes open, and people rarely remember them. Nightmares happen later in the night and people usually wake up and remember them.

A 2002 study in Sleep looked at 10 adults with sleepwalking, night terrors or both, and 10 matched volunteers, over three nights in a sleep lab. Breathing events were more frequent in the people with these parasomnias, and breathing effort seemed to set off many of their arousals and episodes. The authors concluded that sleep-disordered breathing often goes along with these deep-sleep parasomnias.

Can sleep apnea make you act out your dreams?

Sleep apnea can cause movements and shouting in sleep that look like acting out dreams. A 2005 study in Sleep described 16 people who came to a sleep clinic with dream-enacting behavior and unpleasant dreams, along with snoring and daytime sleepiness. Their symptoms suggested REM sleep behavior disorder, a condition where the body doesn't stay still during dreams.

Video sleep studies told a different story. The behaviors happened only as people roused from breathing pauses, and all 16 had severe sleep apnea, with an average AHI of 67.5. CPAP stopped the abnormal behaviors, the unpleasant dreams, the snoring and the daytime sleepiness. The authors said a video sleep study is needed to tell the two conditions apart. Our guide to what happens at a sleep study explains how that works.

Does CPAP stop nightmares?

CPAP often reduces nightmares in people with sleep apnea. In the 2013 study of people with sleep apnea and nightmares, researchers checked in three months later. Nightmares had disappeared in 91% of those who used CPAP well, compared with 36% of those who declined treatment.

CPAP can also change dreaming more broadly. In the 2006 study of severe sleep apnea, people remembered a dream after about half of REM awakenings before treatment. That fell to 20% in the first month on CPAP and 24% at three months, then came back to 39% after two years. The violent and highly anxious dreams seen before treatment disappeared. The researchers linked the drop in dream recall to sleep returning to normal. The same study found REM density, a measure of eye movement during REM sleep, was highest on the first CPAP night, even though dream recall went down.

If CPAP feels hard to stick with, our guide to getting used to CPAP has practical tips.

How are PTSD, nightmares and sleep apnea connected?

PTSD, nightmares and sleep apnea often travel together, and treating the sleep apnea can ease nightmares. A 2017 meta-analysis of 12 studies estimated that about 76% of people with PTSD had at least mild obstructive sleep apnea (an AHI of 5 or more) and about 44% had an AHI of 10 or more. It also found people with both conditions used CPAP less than people with sleep apnea alone.

When they do use it, the results are encouraging. A 2014 study looked at the records of 69 veterans with PTSD and sleep apnea. After CPAP, their average number of nightmares fell from about 10 a week to about 5, and daytime sleepiness scores dropped from about 15 to about 9. Better CPAP use predicted bigger drops in nightmares.

A 2019 meta-analysis of six studies backed this up. CPAP significantly improved both nightmares and overall PTSD symptoms in people with both conditions, and improvements in PTSD symptoms were tied to how well people used CPAP. The authors called for a team approach, with sleep and mental health care working together.

If you live with PTSD and have nightmares, it's worth asking whether a sleep test makes sense, especially if you snore or wake gasping. Sleep apnea treatment isn't a replacement for trauma-focused care, but it can take one strain off your nights.

What else can cause nightmares and night terrors?

Many things besides sleep apnea can cause nightmares and night terrors, so it's worth looking at the whole picture. The NHS lists being very tired or unwell, sudden noises at night, needing to pee during the night, and frightening or stressful experiences as common causes. It adds certain medicines such as antidepressants, restless legs syndrome, generalised anxiety disorder, Parkinson's disease and severe injuries, after which sleep may be disturbed for four to six weeks. Night terrors are also more common in people whose relatives have had night terrors or sleepwalked.

The 2006 study of 323 people with sleep apnea pointed the same way. Psychiatric conditions and psychiatric medicines were more closely linked with nightmares than the severity of the sleep apnea, and some people connected their nightmares to daytime stress.

The NHS says most night terrors and nightmares get better on their own. It suggests a relaxing bedtime routine, dealing with sources of stress where you can, and keeping a sleep diary of how long you sleep, how long it takes to fall asleep and how you feel the next day, which can help spot a pattern.

When should you see a doctor about nightmares?

You should see a doctor about nightmares if they happen regularly and affect your sleep or daily life. That's the NHS's guidance for adults, and it applies whether or not you think sleep apnea is involved.

Mention any signs of sleep apnea at the same time. Loud snoring, breathing pauses a partner notices, waking up gasping and heavy daytime sleepiness all suggest a sleep study is worth doing. Our guides to sleep apnea warning signs and waking up gasping for air can help you describe what's happening. If you're also struggling to stay asleep, see sleep apnea and insomnia.

For someone having a night terror, the NHS suggests staying calm, not trying to wake them and only stepping in if they might hurt themselves or someone else.

This article is general information, not medical advice. Talk to your doctor about your own sleep.

Read next

• 10 warning signs of sleep apnea you shouldn't ignore
• Getting used to CPAP
• Sleep apnea and depression

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.