Night Terrors vs Nightmares: What's the Difference?

Quick answer: Night terrors happen during deep NREM sleep, usually in the first half of the night, and the sleeper is not awake or aware — they often do not remember it. Nightmares happen during REM sleep, usually later in the night, and the sleeper wakes up, recalls the dream, and feels frightened. They are different events with different causes.

Both can leave a household shaken, but night terrors and nightmares are not the same thing. One involves a sleeper who is asleep and unaware; the other involves a sleeper who wakes with a memory. Telling them apart matters, because the causes and the right response differ. This guide walks through night terrors vs nightmares, and explains when either one needs medical attention.

Night terrors — also called sleep terrors — are episodes of intense fear, screaming, or thrashing that occur while the person is still asleep. They look dramatic, but the sleeper is not conscious of them.

Night Terrors vs Nightmares: The Core Differences

The easiest way to separate the two is timing and memory.

• Sleep stage: Night terrors arise from deep NREM (N3) sleep. Nightmares arise from REM sleep.
• Timing: Night terrors cluster in the first third of the night. Nightmares usually appear in the second half, when REM periods lengthen.
• Awareness: During a night terror, the person is asleep and unresponsive. During a nightmare, the person wakes up.
• Memory: Night terrors are usually not remembered, or only vaguely. Nightmares are vividly recalled.
• Behavior: Night terrors can involve screaming, sweating, a racing heart, and thrashing. Nightmares involve waking in fear with a clear story.

If someone wakes up and tells you about a monster chasing them, that is a nightmare. If someone is screaming with their eyes open but cannot be comforted or woken properly, that is more likely a night terror.

What Night Terrors Look Like

A night terror can be alarming to watch. The sleeper may sit up suddenly, scream, breathe fast, sweat, and look terrified. Their eyes may be open, but they are not seeing the room. Episodes usually last a few minutes and end as suddenly as they began, after which the person settles back to sleep.

Children between about three and twelve experience night terrors most often, and many outgrow them. Adults can have them too, particularly under stress, with sleep deprivation, or with certain conditions.

It helps to know that during a night terror the brain is not in a dreaming state in the way REM is. This is why the person cannot describe a dream afterward — there is no narrative to recall. For a deeper look at the dreaming stage, see what is REM sleep.

What Nightmares and Nightmare Disorder Look Like

Nightmares are vivid, distressing dreams that wake you up. Everyone has them occasionally. When they become frequent, cause significant distress, or disrupt sleep and daytime functioning, clinicians may call it nightmare disorder.

Signs of nightmare disorder include:

• Nightmares most nights, or several times a week
• Waking in fear with a racing heart
• Reluctance to go to sleep
• Daytime fatigue and low mood
• Difficulty concentrating the next day

Nightmares often increase during stressful periods, after trauma, or with certain medications. They also occur more in people with narcolepsy symptoms and other REM-related conditions.

Why These Episodes Happen

Night terrors and nightmares share some triggers even though their sleep stages differ:

• Sleep deprivation and irregular schedules
• Stress, anxiety, and trauma
• Fever and illness, especially in children
• Alcohol and some medications
• Sleep apnea, which fragments sleep and can trigger episodes

Other parasomnias can overlap. In REM sleep behavior disorder, people physically act out dreams and may injure themselves. In sleep paralysis causes, the sleeper wakes unable to move. Teeth grinding, covered under bruxism and teeth grinding, is another night-time behavior that can disturb sleep.

What Actually Helps

The right response depends on which problem you are facing.

For night terrors:

• Do not try to wake the person forcefully; stay calm and keep them safe
• Guide them gently away from hazards such as stairs or sharp edges
• Keep a consistent sleep schedule to reduce deep-sleep disruption
• Address any sleep apnea or stress triggers

For nightmares:

• Practice relaxation before bed
• Consider image rehearsal therapy, in which a recurring nightmare is rewritten with a calmer ending — a technique supported by sleep specialists
• Keep a regular sleep routine
• Talk with a clinician if nightmares follow trauma

For both, protecting sleep quality helps. A comfortable sleeping position can reduce awakenings, and treating underlying sleep problems often reduces episodes.

When to See a Doctor

Occasional episodes are usually harmless. Seek medical advice when:

• Episodes are frequent or getting worse
• Someone is at risk of injury during an episode
• Nightmares cause lasting fear, anxiety, or avoidant behavior
• Daytime sleepiness or mood changes appear, such as excessive daytime sleepiness
• Snoring, gasping, or pauses in breathing occur

A clinician can rule out sleep apnea and other disorders. If you need care, a sleep doctor near me search is a good starting point.

Frequently Asked Questions

What is the main difference between night terrors and nightmares?

Night terrors happen in deep NREM sleep, usually early in the night, and are not remembered. Nightmares happen in REM sleep, often later, and are vividly recalled on waking.

Are night terrors dangerous?

They are usually not dangerous, but a person can hurt themselves by thrashing or walking during an episode. Keeping the area safe is the priority.

Do children outgrow night terrors?

Many children do outgrow them by adolescence. If episodes are frequent, cause injury, or continue into the teen years, an evaluation is worthwhile.

Can adults get night terrors?

Yes. Adults can have night terrors, often linked to stress, sleep deprivation, alcohol, or another sleep disorder such as sleep apnea.

When should I see a doctor about nightmares?

See a doctor if nightmares are frequent, disrupt your sleep, cause ongoing distress, or come with daytime sleepiness or other symptoms.

Final Thoughts

Night terrors and nightmares can both rattle a home, but they come from different sleep stages and call for different responses. Night terrors pass without memory; nightmares wake you with a story you wish you could forget. If either is frequent, treat it as a signal rather than something to endure. Track the pattern, then find a sleep clinic near you if it keeps disrupting your nights.

This article is for general information only and is not a substitute for professional medical advice. See a doctor or sleep specialist for diagnosis and treatment.

Related reading

• Narcolepsy: symptoms, causes and diagnosis
• Excessive daytime sleepiness
• The best sleeping position for better sleep