Why Nightmares Are Your Brain’s Rehearsal for Survival

I am no stranger to nightmares. Post-trauma I was diagnosed with night terrors and insomnia, and boy did I learn just how horrifying night-terrors could be. There were nights I would wake up screaming and more than once I woke up having pulled muscles in my sleep. Nothing haunts your waking life quite like limping around on the calf you pulled while running from zombies that night.

I became obsessed with them during my waking life and needed to find some way to stop my mind from replaying them over and over again. I tried turning them into poetry to make them more beautiful, I tried writing different endings to them (my husband’s idea), I tried just about anything I could think of to get the nightmares out of my head and out of my way of living.

Eventually one of my doctors told me to maybe start listening to them instead of ignoring them or changing them. That set me off a whole spiral of looking into the why of nightmares. Turns out in your mind, your old star-chart and survival map, lights up in strange ways when you fall asleep.

Sometimes there’s a hallway you can’t quite escape, or a wave like those giant ones in Interstellar, or sometimes a face you love looking away in annoyance at you. I run without traction like I’m stuck in slow motion, zombies chase me and the dead grab at me with their fleshy fingers, I scream but no sound comes out no matter how hard I try. Whatever it is, the nightmare feels alarmingly real, and the scene of horror that shook you to your core wasn’t there to torment you, it was there to train you.

This isn’t new-age optimism or some fluffy shite someone on the internet is spouting at you (okay, maybe it’s me and yes, I am a little bit). It’s actually one of the oldest ideas that your nervous system is trying to simulate danger while the stakes are low, so you can react faster when the world comes crashing in on you in life.

The internet calls it something like, Threat Simulation Theory, but I really don’t care what you call it. I actually felt some relief that there was a reason my brain tormented me all these years post-trauma.

Behind the bad dream

REM (rapid eye movement) is where the theater of dreams gets its time to shine. During REM, PubMed says that metabolic activity in the limbic and paralimbic circuits (Google translates that to the brain’s emotional command center) rises while parts of the rational prefrontal cortex dims.

It’s sort of like putting your feelings front and center while the part of your brain responsible for making sure things make sense steps out for coffee. Neuroimaging has shown increased activation of the amygdala and anterior cingulate during REM, these are the regions that light up with threats and signal alarm. Knowing that, it’s not shocking that REM is the playground for vivid, emotional dreams.

I even found evidence from Wiley Online Library saying the human amygdala spikes with that rapid eye movements themselves, as if every tiny dart of the eye is somehow setting off those alarm signals.

Okay, so here comes the good part: why would evolution do this? Is it just a masochistic a-hole that likes messing with us?

So, lots of theories online obviously, but one caught my eye in particular, and that’s the idea that dreaming evolved to stage risk scenarios again and again, letting the brain sharpen it’s reflexes and flight simulations without paying the real-world price. Practice is power.

When a system can rehearse stress while the body is actually safe in a nice comfy bed, it can later recognize patterns faster and react more efficiently in real life. That’s the Threat Simulation Theory in its essence.

I liked this theory for more than one reason. Obviously it’s nice to know that my brain doesn’t hate me and isn’t just enjoying the fear it can create, but also because this is in a weird way what I’m trying to do with Blockchain Botany. In my digital game I’m simulating all the risks and rewards of the cryptocurrency world, but without any of the real stakes. Practice makes your mind understand without putting your livelihood on the line. It’s interesting to see my waking mind is subconsciously borrowing the strategies of my subconscious.

Not just wolves anymore

Our ancestors’ nightmares probably wore fangs and featured cliffs, predators and ambushes.

Yours can look like missed flights, lost phones, social nightmares, or brakes that won’t catch in your car while you’re driving in the rain. Mine often heavily feature zombies and people’s heads being blown off. Different costumes, same nervous system.

Your subconscious builds the props from whatever is on today’s workbench, maybe emails you avoided, the near-miss at the light, or a lingering memory that still shivers up your spine when you’re least expecting it. Our brains swapped out a saber-toothed tiger for a spinning wheel of modern stressors, but the basic principle reamains unchanged. Test the alarm, strengthen the circuits of panic, and rehearse the exit.

The gist of yet another study I stumbled upon when trying to soothe my mind from my nightmares was that we remember the information of our dreams while forgetting the sharpness of the emotions that came with it. Reviews by Walker and colleagues gathered a decade of findings linking REM to emotional memory processing and next-day affective recalibration. AKA you wake with the lesson your brain wanted you to learn and some of the sting sanded away. It’s not erasure, it’s integration.

If you’ve suffered from nightmares like me you might be feeling a little betrayed by your mind right now. If they’re supposed to be an ancient training tool, why do some people get it so much worse than others?
Well, tools can be overused or mis-calibrated basically. In circumstances like acute stress, trauma, or chronic anxiety, the simulation engine may loop a touch too loudly, failing to complete its integration work. So, sadly, instead of your mind taking it’s lessons and removing the sharpness behind them, it grates against your consciousness like sandpaper on your elbow.

But what if you don’t remember your nightmares?

Ahh, my hope for you, wherever you are in the world and whatever you’re going through is that your nightmares fade and you never ever remember them. That’s okay. Remembering is not actually needed for the training your brain is doing to work. A lot of the plasticity happens under the mysterious threshold of recall. Your body runs the maze even if the story evaporates by breakfast, and instinct and reflexes are still programmed into you while you close your eyes.

Practical ways to work with a hot rehearsal loop

This is not medical advice; if your nightmares are frequent, severe, or linked to trauma, please talk with a clinician trained in sleep or trauma care. These practices complement, not replace, professional treatment and are just my own personal experience with trial and error.

Right after a nightmare, jot a two-minute synopsis of your dream, then write an alternate ending. And I don’t mean a perfect ending where you live happily ever after, just slightly safer. The brain loves a direction to move in and might be able to take it from there.

Spend 5 minutes with the new ending, eyes open, and breathing slow. See it in your mind, feel it, and finish it so it’s complete in your brain. Repeat this process daily for a week. This mimics the structure of imagery rehearsal therapy and has helped me a lot in the past.

Before sleep and after waking up, insert a 90-second block of slow nasal breathing. It’s not magic, it just turns down the sympathetic drive so the next night’s rehearsal begins with a slightly calmer baseline.

Treat the last hour before bed as dim and quiet. Use blue-light blocking screens on your phone and computer if at all possible. You’re priming the hypothalamus and pineal with more soothing signals and less alarm. The fewer blue-white alarms you send through the retina at night, the less jitter your mind carries into REM.

If you’ve experienced severe trauma, please work with a professional. Therapies like IRT, EMDR, and trauma-focused CBT can help re-index memories so the rehearsal stops looping. The goal isn’t to tear the page out, it’s to file it where it belongs.

Common nightmare motifs

I’ve had all of these fairly often in my past and have Googled them ad nauseam at this point and can probably tell you immediately without skipping a beat anymore.

Falling is a big one. Often tied to instability, loss of control, or a sudden transition. The rehearsal in theory is to recognize destabilization early and practice softening on impact.

Teeth crumbling or never ending gum you just pull and pull and pull. Classic anxiety imagery. Endure social pressures and learn to tolerate perceived “flaws” without collapsing in on yourself.

Being chased is an archetypal threat cue. The rehearsal is for you to scan exits faster, set boundaries sooner, and be able to mobilize without panic. I struggle with these almost daily.

Inability to speak is linked to performance/voice fears. Breath first, words next; clarity over volume.

Ever have a dream that you’re late for an exam? Basically this is your mind scolding you for procrastinating something in your life.

These aren’t fortune-cookie meanings, they’re just working hypotheses your mind is testing in the dark.

What about lucid dreaming?

If your brain sometimes flips you realize mid-scene you’re dreaming, wonderful!! Lucidity can be a gentle place to practice facing your fears. You don’t have to fly (but also, I always choose to), instead you can turn to face the thing that chases you, or slow the scene. The point isn’t heroics, it’s choice and what you do with it.

We talk about nights as if they’re completely separate from days, but the nervous systems don’t punch timecards. The load you carry at noon shows up on the REM stage at 2 a.m and the nightmares that haunt your dreams can bleed over into waking life.

Try some sunlight before screens in the morning if you can. Ten minutes of morning light helps anchor circadian timing so REM clusters more cleanly near dawn, where it belongs.

Enjoy caffeine with boundaries, your amygdala has enough fireworks.

A confession from someone who’s listened to hundreds of nightmare stories: the moment you soften around the fear, the scene changes. When you stop declaring war on your own alarms, you give REM a safer room to conduct its practice. Over time, this miight mean fewer alarms, cleaner drills, better sleep, and even steadier days.

The science is still writing itself

Of course the world doesn’t really have the answers just yet.

Does Threat Simulation Theory explain all dreams…no.

Dreams are a menagerie we might never truly understand. Some are memory housekeeping, some are wild art, some are the brain’s default-mode machinery scattering sparks because that’s what neurons like to do in their free time. But the weight of evidence says nightmares play a part in threat modeling. That idea has matured from Revonsuo’s early formulation into a broader landscape of models that still hover around the same truth: dreaming is for adaptation.

The dream is not the enemy, it’s more like the coach who loves you enough to run the drill again and again until your legs are shaking and your chest heaving.

And if the coach is screaming in your face and the drills are too hard, that doesn’t make you any less than. You deserve a night that heals and dreams that don’t linger longer than they should.