The Tetris Effect stole my sleep

The bedroom is quiet and cool, the bed is soft, the sheets are smooth. I lie down and relax, so sleepy that not even a daydream will stay in my head. I drift off...only to see the game I played before bed vividly in front of my eyes. It repeats over and over and over again forming the same patterns.

I have been playing a clicker RPG on my phone for the last few days. It is a game where your damage is determined by how fast you can tap the screen, and you have a team of followers who deal constant DPS. The numbers rise exponentially with each new follower. Last night, I entered an in-game tournament. This made me spend more than an hour on it directly before going to sleep.

It looks like that the pattern of taps and numbers has gotten stuck in my brain. All night, in the non REM sleep stage, where I should have been comfortably unconscious and resting, has this game been playing in my mind. Where I should have seen random scenes and lines of sleep, I have seen coins explode out of beaten enemies. Even in my dreams, things kept increasing exponentially; tens, then hundreds, then thousands, then millions...

Yesterday's game isn't the first game to cause this for me. The most annoying side effect was from Diablo 1. I was constantly going down to lower levels for several nights. Ingress has also had a strong effect. I was making lines and triangles not only in my half sleep hallucinations, but in my nightly dreams.

This is called the Tetris Effect. It isn't limited to computer games. My mother has told me about how she has spent entire nights with visions of knitting after learning new patterns. Psychologists think this has something to do with learning and subconsciously forming memories. I think it means that I played that game too much yesterday.

Melatonin changes my sense of time

I work shifts, and that isn't good for my already unusual sleep rhythm. To battle the sleeplessness and following zombie state every time my schedule changes, I got some melatonin pills. Melatonin is a hormone that is produced naturally in the body when it is dark. It is a part of the system that signals the body when it is time to fall asleep.

It does, usually, make me fall asleep faster. It also makes me wake up earlier, which is a good thing when the alarm rings at 6 AM. After taking a melatonin pill before midnight, it feels like I have had a fuller night of sleep early in the morning. It is easier to drag myself out of bed.

What I didn't expect was the effect the drug had on my experience of time. I don't just wake up as easily after 6 hours with melatonin as after 9 hours without, it also feels like it has literally been 9 hours since I fell asleep. I have often woken up at 3 or 4 and thought I have overslept, because my sense of time has been wrong. I have woken up half an hour before my alarm in a panic, because I have been certain that I overslept!

We all wake up several times every night. Many people can't remember this. I usually do. When I take melatonin, I notice the awakenings even more, because there is usually some anxiety involved. It is harder to fall back asleep when my stomach is a tight knot and my mouth is dried out. Sometimes, I am sure that I have been lying still in bed, trying to sleep, for more than an hour. Then I look at the time. It has only been 20 minutes.

The altered sense of time lasts into the morning sometimes. It can feel like I have spent half an hour in the bathroom, and that I have certainly missed my bus, when it has only been 10 minutes. This is really fun when work is slow.

I have asked other people on IRC and on LD4all for their experiences, and nobody else has experienced this side effect. It isn't stopping me from using the pills now and then. I'd rather have a moment of panic in the morning than a full shift as a zombie.

The randomness has a name: Hypnagogic hallucinations

You lie in bed, waiting for sleep to come. Your thoughts spin around everything that has happened in the day, and everything you will have to do the next day. As your body gets more and more relax, it gets harder and harder to follow the train of thoughts. The mind jumps randomly around, and strange ideas insert themselves into your mind. You find yourself looking at something, and it takes a moment to realise that it isn't real. Random lines flash past you in your thoughts. You are walking, and suddenly, you slip through the ground. Your body jerks, and you are startled awake.

This is called hypnagogic hallucinations, hypnagogic images or sleep images.

Hypnagogic hallucinations are normal

Phosphenes, as they usually look to me

Most of us experience this phenomenon regularly. It is extremely common to hallucinate while falling asleep. These hallucinations are a normal part of the process of falling asleep, and not in any way connected to mental illness.

The first and simplest kind of hallucinations is called phosphenes. When there is no visual input from the eyes, background noise from the nervous system will become visible as shapeless blobs of light. For me, they are usually blue or green. Staring at the darkness for a few moments is usually enough to induce the hallucination, and the longer I focus on it, the stronger it becomes.

This isn't necessarily a sign of falling asleep. Phosphenes can have other causes, such as pressure (for example from rubbing your eyes) sleep deprivation, or fever.

Visual hallucinations are common while falling asleep. After intense activity, especially after learning a new skill such as a computer game, visual hallucinations can be very detailed copies of the activity. This is called the Tetris effect. Other common themes are text or headlines, shifting patterns, landscapes and work scenes. Maybe my most common visual scene is the workbench in the flower shop where I work. It is welcome, because it simply means that I'm falling asleep. For a person with periodic insomnia, this is a relief.

All senses can be affected

The hallucinations aren't necessarily visual. It is just as normal to experience sounds and physical sensations. I have been lucky enough to hear music several times. The music can be a well known song, or it can be completely new. Some people hear their own thoughts spoken by their own voice. Footsteps, the doorbell, or a phone ringing are commonly reported sounds. Some people may experience an extremely loud noise. This is known as exploding head syndrome. It is rare, and harmless.

It can feel like the body is being stretched, compressed, lifted up or vibrating. I sometimes feel like my hands are floating in thin air. Some people have even reported smells or tastes. I know that I have hallucinated the smell of smoke at least once.

The hypnic jerk

A specific kind of hallucination can actually be so disturbing that we wake up. It's a startle reaction called the hypnic jerk. It feels like a "jump", and is usually accompanied by hallucinations of falling or slipping. For me, it usually feels like I fall "through the ground". This is apparently more common in stressful periods. Sometimes, after sleep deprivation, this is how we can notice that we are actually falling asleep in the day.

Hypnagogic hallucinations and lucid dreaming

Many of my lucid dreams start with this

For people who practice the WILD form of lucid dreaming, the hallucinations are valuable. They are a good sign that the body is actually falling asleep. The hallucinations can transform seamlessly into a dream. The trick is to stay focused on the images, while still allowing sleep to happen. This will usually take some practice.

For me, the best hallucination to get a WILD from is an image of a road or path. It feels easy to concentrate on. I imagine moving along the path, and at a certain point, the illusion shifts from 2D to 3D. When I stand on the road, the lucid dream has started.


For learning more about lucid dreaming, I strongly recommend paying a visit to LD4all. I have learned so much from the people there.

Sleep Paralysis: annoying, maybe frightening, but harmless

You wake up in bed, only to find out that you can't move. Not a single body part obey you, apart from your eyes. Your mind is partially clouded. Are you dreaming, have you been drugged, is something horribly wrong with your body? Something at the edge of your vision catches your attention. A tall, dark shadow stands between you and the window, slowly moving closer to your bed, not making a sound. You can't take your eyes off this threatening vision, and you try to scream, but no sound comes out...

Shadow hallucination. Bedroom photo by Aphoticbeauty

What is sleep paralysis?

If this sounds familiar to you, you have experienced sleep paralysis. The experience is most common immediately after waking up, and usually lasts for a few seconds. Because of the fear that can accompany sleep paralysis, those seconds can feel horribly long.

To understand what sleep paralysis is, we need to know a couple of things about sleep. Sleep is divided into several different phases: NREM 1, 2, 3, and REM. Every time we sleep, we cycle through those phases roughly once every 90 minutes. REM sleep is the phase where we usually dream. In this stage, the body (except the eyes) is completely paralysed. This is called REM atonia. If this paralysis didn't occur, we would have acted out all our dream, and potentially injured ourselves. When we wake up quickly, and directly from REM sleep, consciousness may return before we regain control over our muscles. This causes conscious sleep paralysis.

Hallucinations in sleep paralysis

It is common to hallucinate in this state. The scientific word for hallucinations upon waking up is hypnopompic hallucinations. Several theories try to explain where these hallucinations come from; some say that they are a result of natural brain processes during sleep which imitate stress and fear reactions, and some say that they are simply background noise from the brain. A common hallucination is seeing, hearing or otherwise sensing an intruder in the bedroom. As soon as we wake fully, the hallucination dissolves. Seeing a dark, humanoid shadow is an especially common hallucination. I used to experience this often in my youth. Now, I usually hallucinate footsteps, the doorbell, or a cat curled up on my bed.

Simply knowing that this is a hallucination helps against the fear. It is good to know that this isn't real, it is harmless, and will go away at least a few moments after muscles start working again. Most people experience this at some point. Some people experience it as much as once a week, and that can be a sign of an underlying sleep or anxiety disorder.

How do I get rid of it?

It is common to experience sleep paralysis more often if we are stressed or anxious. I have also heard stories of this happening after overuse of alcohol, tobacco, caffeine, or other psychoactive substances. Keeping a healthy sleep schedule and otherwise treating the body well may help prevent it.

Apart from the eyes and face, the first body parts to regain control are often the fingers and toes. It can be effective to focus on them. When control comes back in a finger, the rest of the body should follow within moments. I have often made the mistake of focusing on my voice first, and that has just added more stress.

If the hallucinations aren't too distracting, simply going back to sleep is also an option.

Many lucid dreams start like this

Sleep paralysis and lucid dreaming 

It is possible to experience paralysis both while falling asleep and while waking up, even if the latter is far more common. For people who are familiar with the WILD (Wake Induced Lucid Dream) technique, sleep paralysis can be used as an easy way into a lucid dream. The brain is already close to REM sleep. Some people have described how they simply roll out of bed, stand up, and find themselves in a fully formed lucid dream. It is probably a good idea to at least make it a habit to do a reality check after every sleep paralysis experience.

Further reading

LD4all's SP FAQ

Wikipedia article


First published April 2015, updated March 2026