Sleep Hallucinations: Hypnagogic, Hypnopompic and EHS

It happens to me once in a while: I hear one of my kids calling me from their bedroom, the front-door doorbell, that sharp smoke-alarm beep, or even an explosion. It’s so brief that once I’m up, I think, “No, it’s never that short in real life.” And that’s usually when I realize: it wasn’t a sound from the world, it was a threshold sound.

Different names for the same in-between

When these perceptions show up as you’re falling asleep, they’re called hypnagogic hallucinations. When they happen as you’re waking up, they’re hypnopompic hallucinations. In both cases, the setting is the same: a transition zone where the brain hasn’t locked the door yet between wakefulness (where you check, doubt, compare) and sleep (where you accept a story without asking for proof).

There’s also a more spectacular cousin: Exploding Head Syndrome (EHS). Despite the name, it isn’t dangerous, but it’s startling: a sudden, extremely loud noise, like a bang, an explosion, or an impact, right as you’re falling asleep or waking up. Again, the sound is an illusion, but the adrenaline is very real.

The strangest thing about audio is how believable it is. A weird image can be debated. A beep, a call, a doorbell: those are coded as “emergency,” “presence,” “respond now.” Our alarm system loves those sounds.

My brain, the impatient foley artist

In that in-between state, the brain can “import” a fragment of a dream and give it the texture of reality. It often picks sounds with strong emotional weight: a child’s voice, a household signal, a device malfunctioning. One sample is enough, half a second, and the whole body reacts.

These episodes are usually brief, and many people eventually learn to recognize them, especially when the sound cuts off abruptly, with no natural reverberation, without waking anyone else, with no logical follow-up, no context. That’s exactly my clue: too short, too clean, too “isolated.”

Why does it happen more on certain nights?

In my experience, there are conditions that make these intrusions more likely: fatigue, stress, a shifted schedule, broken sleep. Your attentional resources are worn down, and the brain fills in the gaps. Certain medical situations can also increase how often it happens: sleep disorders (like narcolepsy), episodes of sleep paralysis, or the effects of substances or medications in some people.

My go-to ways to tame it

First, I do a minimal check without launching a nighttime investigation. Once I’m reassured, I avoid feeding the alarm response. I also have a few habits that reduce the chances of these “phantom beeps”:

I soften the landing: low light, no late-night screens, a more regular bedtime. I unload my mind: a quick note of tomorrow’s to-dos, so they don’t turn into sirens at night. And I take real-world audio seriously: if I’m fixated on a detector’s beep, I handle it during the day (battery, placement, maintenance). Paradoxically, it’s better to solve a real beep than to endure a fake one on repeat.

When to talk to a professional

If these hallucinations become frequent, very distressing, if they spill into daytime, or if they come with signs like marked daytime sleepiness, emotionally triggered loss of muscle tone, or repeated episodes of sleep paralysis, don’t hesitate: start with your primary care doctor, then a sleep specialist if needed. The goal isn’t to dramatize, but to confirm you’re dealing with “transition noise” and not something else.

At the end of the day, these moments remind me of one thing: the ear isn’t a simple microphone, it’s a stage. And sometimes, at the exact moment I leave the control room, my brain fires off a sound effect just to see if I’m still there.

And you, what sound does your night play most often: a voice, a doorbell, a beep… or something else entirely?