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# NREM parasomnias and nightmare disorder

- Disorder

Unwanted events during sleep: sleepwalking, night terrors and confused arousals from deep sleep, and frequent frightening dreams that wake a person.

Updated Nov 13, 2026

## Key points

- NREM parasomnias: early in the night, from N3, hard to wake, little or no memory of the event.
- Nightmares: later in the night, from REM; the person can wake fully and recall the dream vividly.
- Sleep terrors: sudden screaming and flailing; the child looks frightened and intensely activated, is hard to wake and falls back asleep after a few minutes.
- Triggers make NREM events more likely: sleep deprivation, excessive fatigue, fever, mental distress, alcohol, sedative-hypnotics and sleep fragmented by sleep apnea.
- Treatment of NREM parasomnias is mainly reassurance, safety and avoiding triggers; for nightmares, imagery rehearsal therapy is used, and prazosin for PTSD-related nightmares.
- Nocturnal seizures can mimic parasomnias; video EEG with polysomnography helps tell them apart.

## What it is

NREM sleep arousal disorders (sleepwalking, sleep terrors and confusional arousals) are incomplete awakenings from deep N3 sleep, usually in the first few hours after falling asleep, during which the person is hard to wake and remembers little or nothing afterwards. They are more common in children, run in families, and children tend to outgrow them. Nightmares are frightening dreams from REM sleep, which predominates later in the night; the person can wake fully and recall the dream vividly, and frequent nightmares bring distress and daytime impairment. REM sleep behavior disorder, the acting out of dreams in older adults, has its own page.

## Key facts

- Confusional arousals are partial awakenings from slow-wave sleep with confusion and disorientation.
- About one in three children with sleep terrors also sleepwalks, and sleepwalking peaks around age 10.
- Sedative-hypnotics can trigger confusional arousals, and zolpidem can bring on sleep-related eating.
- Nightmares occur more often during stress, and in PTSD they are among the most common, distressing and chronic symptoms.
- Nightmares and insomnia in PTSD bring significant distress and daytime impairment, so they are worth asking about.

## Night-time events compared

| Event | Stage and timing | Behavior | Memory afterwards | Typical age |
| --- | --- | --- | --- | --- |
| Sleepwalking | N3, first hours of the night | Gets up and walks; sometimes complex acts | Usually none | Late childhood and adolescence |
| Sleep terrors | N3, first hours of the night | Screams, flails, looks frightened and intensely activated, hard to wake | Not recalled in detail | Ages 3 to 8 |
| Confusional arousals | Slow-wave sleep | Confusion and disorientation | Poor recall | Children |
| [Nightmare disorder](https://durgical.com/en/conditions/post-traumatic-stress-disorder-and-acute-stress-disorder/) | REM, later in the night | Wakes frightened, can wake fully | Vivid, detailed dream | Childhood and times of stress; adults with PTSD |
| [REM sleep behavior disorder](https://durgical.com/en/conditions/rem-sleep-behaviour-disorder/) | REM sleep | Acts out dreams | Vivid dream recall | Men over 50 |

## Clinical notes

- Reassure families of children with NREM events and explain the condition; children tend to outgrow them, and usually no treatment is needed.
- Make the sleeping area safe: locks and door alarms, a low bed, and removing firearms, sharp objects and furniture near the bed.
- Ensure enough sleep, avoid triggers such as sleep deprivation, alcohol and other central nervous system depressants, and treat sleep apnea.
- Benzodiazepines, particularly clonazepam at bedtime, can help when behavioral measures are not enough; nightmares are treated with imagery rehearsal therapy and, in PTSD, sometimes prazosin.

## Memory aid

Early night, Empty memory: NREM event. Late night, Lively memory: nightmare.

## Test yourself

Think of the answer, then tap the question to see it.

## How do sleep terrors differ from nightmares in timing and memory?

Sleep terrors arise from N3 sleep in the first hours of the night and are not recalled in detail; nightmares arise from REM sleep later in the night and can be vividly remembered.

## What is the first-line approach to childhood sleepwalking?

Reassurance, enough sleep, avoiding triggers and making the home safe; usually no medicine is needed.

## What psychological treatment is specific for nightmare disorder?

Imagery rehearsal therapy: rewriting the nightmare's storyline while awake and rehearsing the new version every day.

## Which tests help tell nocturnal seizures from a parasomnia?

Video EEG with polysomnography.

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## Elsewhere in DurgiPedia

- [Wakefulness, sleep, the EEG and seizures](https://durgical.com/en/physiology/wakefulness-sleep-the-eeg-and-seizures/)
- [Promoting sleep in hospital](https://durgical.com/en/nursing/promoting-sleep-in-hospital/)

## Connections

## Related 5

- [Sleep stages and their EEG](https://durgical.com/en/behavioral-science/sleep-stages-and-their-eeg/)
- [Normal sleep across the life span](https://durgical.com/en/behavioral-science/normal-sleep-across-the-life-span/)
- [Hypersomnolence and circadian rhythm sleep-wake disorders](https://durgical.com/en/behavioral-science/hypersomnolence-and-circadian-rhythm-sleep-wake-disorders/)
- [Sleep hygiene and the behavioral treatment of insomnia](https://durgical.com/en/behavioral-science/sleep-hygiene-and-the-behavioral-treatment-of-insomnia/)
- [Cognitive behavioral therapy and cognitive distortions](https://durgical.com/en/behavioral-science/cognitive-behavioral-therapy-and-cognitive-distortions/)

## Related conditions 6

- [REM sleep behaviour disorder (RBD)](https://durgical.com/en/conditions/rem-sleep-behaviour-disorder/)
- [Post-traumatic stress disorder (PTSD) and acute stress disorder](https://durgical.com/en/conditions/post-traumatic-stress-disorder-and-acute-stress-disorder/)
- [Obstructive sleep apnoea](https://durgical.com/en/conditions/obstructive-sleep-apnoea/)
- [Epilepsy and seizures](https://durgical.com/en/conditions/epilepsy-and-seizures/)
- [Restless legs syndrome](https://durgical.com/en/conditions/restless-legs-syndrome/)
- [Parkinson disease](https://durgical.com/en/conditions/parkinson-disease/)

## In Pharmacology 3

- [Clonazepam](https://durgical.com/en/pharmacology/clonazepam/)
- [Prazosin](https://durgical.com/en/pharmacology/prazosin/)
- [Z-drug hypnotics](https://durgical.com/en/pharmacology/classes/z-drug-hypnotics/)

[← All of behavioral science](https://durgical.com/en/behavioral-science/)

Educational content on behavior and the clinical relationship; not a diagnostic or treatment guide and no substitute for assessment by a health professional. If you or someone near you is at risk, seek help now from an emergency service or a mental-health helpline.

Sources: [Parasomnias](https://www.msdmanuals.com/professional/neurologic-disorders/sleep-and-wakefulness-disorders/parasomnias) (MSD Manual Professional Edition, 2026); [Sleep Problems in Children](https://www.msdmanuals.com/professional/pediatrics/behavioral-problems-in-children/sleep-problems-in-children) (MSD Manual Professional Edition, 2025); [Parasomnias: A Comprehensive Review](https://pmc.ncbi.nlm.nih.gov/articles/PMC6402728/) (Cureus (PubMed Central), 2018); [Treating Nightmares and Insomnia in Posttraumatic Stress Disorder: A Review of Current Evidence](https://pmc.ncbi.nlm.nih.gov/articles/PMC5154613/) (Neuropharmacology (PubMed Central), 2012).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/behavioral-science/nrem-parasomnias-and-nightmare-disorder/