Waking someone from a nightmare isn’t dangerous, but it’s usually not the best move either. The main downside is practical: waking someone mid-nightmare makes them more likely to remember the bad dream in vivid detail, which can make it harder for them to fall back asleep. In most cases, nightmares resolve on their own within minutes, and the sleeper never remembers them.
That said, the answer changes significantly depending on whether the person is actually having a nightmare or something called a night terror. These look different, happen during different stages of sleep, and require very different responses.
Nightmares vs. Night Terrors: Why It Matters
Nightmares happen during REM sleep, the lighter dream stage that’s most common in the early morning hours. During a nightmare, the person may twitch, whimper, or make small movements, but they’re relatively still. If you wake them, they’ll usually orient quickly, recognize you, and be able to describe the dream.
Night terrors are a completely different neurological event. They occur during deep non-REM sleep, typically in the first half of the night. A person in a night terror may scream, thrash, sit up, or even get out of bed. Their eyes might be open, but they’re not actually awake. The key difference: if you leave them alone, they won’t remember anything in the morning. Night terrors are especially common in children.
The distinction matters because the advice for each situation is essentially opposite. A nightmare is interruptible. A night terror is not, and trying to intervene can make things worse.
What Happens When You Wake Someone From a Nightmare
Because nightmares occur in REM sleep, the brain is already in a relatively light state. Waking someone up is physically easy to do and poses no medical risk. They won’t be dangerously confused or disoriented. The person will typically wake up alert, though understandably shaken.
The tradeoff is that you’re essentially locking in the memory. A nightmare left to run its course will often fade from memory entirely by morning. Once someone is woken mid-dream, though, the imagery tends to stick. For people who are prone to anxiety or who already struggle with recurring nightmares, this can create a cycle where the remembered content fuels worry about going back to sleep.
If the person seems mildly distressed (murmuring, frowning, restless movement), the nightmare will likely pass on its own. Letting it run its course is usually the better option. But if they’re clearly in significant distress, crying out, or the nightmare has gone on for a while, waking them is perfectly fine.
Why You Shouldn’t Wake Someone From a Night Terror
Night terrors look far more alarming than nightmares. The person may scream, flail, or appear panicked with their eyes wide open. Every instinct tells you to grab them and shake them awake. Sleep experts consistently advise against this.
During a night terror, the brain is in stage 3 deep sleep. Waking someone from this stage is extremely difficult, and even if you succeed, the result is a state called sleep inertia: roughly 30 minutes of intense confusion and mental fog. The person won’t understand what’s happening, won’t recognize why you’re upset, and may become more agitated. Attempting to wake them can actually prolong the episode rather than end it.
Physically restraining someone during a night terror is also risky. Because their brain hasn’t registered that they’re awake, they may push, kick, or strike out without any awareness of what they’re doing. This can injure both you and them.
The recommended approach during a night terror is straightforward: stay nearby, speak in a slow and calm voice, gently guide the person back to bed if they’ve gotten up, and make sure they can’t hurt themselves on furniture, stairs, or windows. Once the episode passes (usually within a few minutes), they’ll settle back into sleep naturally and have no memory of it.
How to Tell Which One You’re Seeing
A few quick signals help you figure out what’s happening:
- Timing. If it’s the first few hours after falling asleep, a night terror is more likely. If it’s closer to morning, it’s probably a nightmare.
- Intensity of movement. Nightmares involve small, restless movements. Night terrors involve screaming, sitting bolt upright, thrashing, or walking.
- Responsiveness. Say the person’s name gently. Someone having a nightmare will often wake or at least respond. Someone in a night terror won’t register your voice at all.
- Eyes open but “not there.” If their eyes are open but they seem to look right through you, that’s a hallmark of a night terror.
If You Do Decide to Wake Them
When someone is clearly stuck in a bad nightmare and you want to intervene, a gentle approach works best. Say their name in a calm, normal voice. If that doesn’t work, try a light touch on the arm or shoulder. Avoid shaking them or shouting, which can spike their heart rate and make the disorientation worse.
Once they’re awake, give them a moment to get their bearings. Let them talk about the dream if they want to, but don’t press for details. Turning on a low light can help their brain confirm that the environment is safe. A glass of water, a few minutes of quiet conversation, or simply sitting with them while they settle down are all more helpful than immediately encouraging them to go back to sleep.
For people who experience frequent nightmares (more than once a week, or nightmares intense enough to affect daytime functioning), the issue is worth bringing up with a healthcare provider. Chronic nightmares can be connected to stress, certain medications, or sleep disorders, and targeted treatments like imagery rehearsal therapy have strong track records for reducing them.