Nightmares vs Night Terrors: What's the Difference?

Both involve distress in the middle of the night. Both can leave someone shaken. But nightmares and night terrors are fundamentally different experiences — different sleep stages, different causes, different presentations, and different approaches to managing them.

Confusing the two leads to the wrong response, which is why the distinction matters.

Nightmares

Nightmares are vivid, distressing dreams that occur during REM sleep — the stage associated with most vivid dreaming, typically in the later hours of the night. Because REM sleep is concentrated in the second half of a sleep cycle, nightmares most often occur in the early morning hours.

What they look like:

• The person typically wakes from them and is immediately alert and oriented
• They can usually describe the dream in detail — what happened, who was in it, the narrative
• The distress is remembered and continues after waking
• They are clearly dreams, in retrospect

Causes: stress, anxiety, trauma, certain medications (especially those affecting noradrenaline and dopamine), sleep deprivation, alcohol, and PTSD, which produces a specific and particularly severe form of recurrent nightmare.

Night Terrors

Night terrors (also called sleep terrors) occur during non-REM sleep — specifically during the deep, slow-wave sleep of the first few hours after falling asleep. They are not dreams in the conventional sense.

What they look like:

• The person may sit up, scream, thrash, or appear absolutely terrified
• Their eyes may be open, but they are not awake — they are in a partial arousal state between deep sleep and wakefulness
• If you try to comfort them, they often don't respond or respond in a confused, agitated way
• In the morning, they typically have no memory of the episode at all
• Children are more affected than adults — night terrors are most common in children aged 3–12

Causes: sleep deprivation, fever (in children), stress, irregular sleep schedules, and genetic predisposition (they run in families). Unlike nightmares, they are rarely caused by psychological content or emotional processing.

The key practical difference

This is what makes the distinction most important: you should not try to wake someone during a night terror.

Waking someone in the middle of a night terror can cause significant disorientation and extend the episode. The correct response is to stay nearby to ensure they don't hurt themselves, speak calmly (even if they don't seem to hear you), and let the episode pass on its own — which it almost always does within five to fifteen minutes.

With nightmares, waking someone and grounding them in reality is appropriate and helpful.

When nightmares become a disorder

Nightmare Disorder is a clinically recognised condition characterised by repeated nightmares that significantly impair sleep, daytime function, or wellbeing. It's distinct from the occasional bad dream everyone has.

The most effective evidence-based treatment is Imagery Rehearsal Therapy (IRT) — a technique where you rewrite the nightmare's ending while awake, then mentally rehearse the new version before sleep. Multiple clinical trials have found IRT significantly reduces both the frequency and distress of recurrent nightmares.

PTSD-related nightmares are treated as part of broader trauma therapy, often with EMDR or CPT, though specific nightmare-targeting interventions (like Prazosin, a medication that reduces nightmare frequency) are also sometimes used.

When night terrors become a concern

In children, night terrors are common and generally benign — most children outgrow them. In adults, frequent night terrors can be associated with sleep-disordered breathing, stress, or (rarely) other neurological conditions, and are worth discussing with a doctor.

Tracking when your nightmares occur — alongside your day logs and stress levels — often reveals patterns that make them far less mysterious.