Hypnagogia is the transitional state of consciousness between wakefulness and sleep. It’s the opposite of hypnopompia, which is the transitional state that occurs before you wake up.

During hypnagogia, it’s common to experience involuntary and imagined experiences. These are referred to as hypnagogic hallucinations. Up to 70 percent of people experience these hallucinations, which can appear in the form of sights, sounds, or even feelings of movement.

Muscle jerks, sleep paralysis, and lucid dreams are also common during the hypnagogic phase.

Let’s break down the science behind hypnagogia, examine what you may experience during this state, and look at why some of the world’s most famous thinkers have tried to induce it.

Neurons in your brain communicate with each other through bursts of electrical activity. This electrical activity can be measured in waves with a machine, called an electroencephalogram (EEG).

An EEG can measure five types of brain waves. From slowest to fastest, these waves are called:

When you’re awake, your brain produces measurable alpha and beta waves, with beta waves being predominant. Once you become drowsy, alpha waves take over.

Stage one is the lightest form of sleep and typically lasts for between 1 minute and 5 minutes. During this stage, alpha waves drop to less than 50 percent of your total brain waves and researchers can observe ripples of slower theta waves.

Hypnagogia occurs during the transitional period of wakefulness to sleep, when alpha waves are decreasing but you haven’t yet reached the first stage of sleep.

During this period, your sense of “here” and “now” transitions from the real world to the dream world. When this happens, people commonly experience:

  • hallucinations
  • lucid dreaming
  • body jerks
  • sleep paralysis

We’ll discuss each of these experiences in more detail below.

During hypnagogia, you start to lose touch with reality as your body prepares to enter sleep. The following are some of the most common effects you may experience.

Hypnagogic hallucinations

French psychiatrist Jules-Gabriel-Francois Baillarger first described hypnagogic hallucinations in the 1840s.

Hypnagogic hallucinations are imaginary events that seem real as you’re on the cusp of falling asleep. Usually, these hallucinations are visual, auditory, or tactile. However, they can also involve your other senses and feelings of movement.

They most often occur in young adults and teenagers and become less common with age. Women are more likely to experience these hallucinations than men.

It’s not clear what causes these hallucinations, but some risk factors include:

Visual hallucinations

In about 86 percent of cases, hypnagogic hallucinations involve visual stimuli. Some of the ways visual hallucinations can manifest include:

  • kaleidoscopes of changing colors
  • the appearance of random geometric patterns
  • flashing lights
  • images of people, animals, or faces

Auditory hallucinations

About 8 to 34 percent of hypnagogic hallucinations involve sounds. These sounds can range from faint noises to loud crashes or bangs. Some of the forms they may appear in include:

  • voices or words
  • music
  • phone ringing
  • doorbell sounds
  • your name

Other hallucinations

In about 25 to 44 percent of cases, people report feelings of:

  • weightlessness
  • flying
  • falling
  • feeling like there’s a presence in the room

The Tetris effect

The Tetris effect is a phenomenon where intrusive images or thoughts enter your head after you perform a repetitive activity. It comes from the name of the video game Tetris.

Video games like Tetris are thought to activate visuomotor processes in your brain in charge of coordinating movement and visual perception. Activation of these processes can lead to hypnagogic hallucinations where you see shapes from the video game before falling asleep.

The Tetris effect isn’t limited to video games. Some people claim to have tactile hypnagogic hallucinations of the feeling of rocks in their hands after long periods of climbing.

Hypnogogic jerks

Hypnagogic jerks are sudden muscle contractions that occur when you’re falling asleep. They lead to sudden and strong contractions of your muscles that may jerk you awake.

These jerks are very common and not a sign of a medical condition. They’re thought to affect about 60 to 70 percent of people.

Sleep paralysis

Sleep paralysis is a feeling of being awake but being unable to move your muscles. It often occurs along with hypnagogic hallucinations in people with narcolepsy.

Although sleep paralysis can be frightening, symptoms usually go away in minutes without any health consequences.

Lucid dreams

Lucid dreams occur when you realize you’re dreaming and you’re able to control the dream or storyline. Some people purposefully try to lucid dream to stimulate creativity.

Some people have tried bringing on hypnagogia as a gateway for creativity. Writer Franz Kafka, for example, experienced dream-like hypnagogic hallucinations when writing in a sleep-deprived state.

Some of the world’s smartest minds used hypnagogia to tap into their creativity. Thomas Edison, Edgar Allan Poe, and Salvador Dali used to nap with a steel ball in their hands so that they would wake when the ball hit the floor.

Researchers at the MIT Media Lab have developed a device they call Dormio, a more advanced way of performing the same technique.

During hypnagogia, people can still hear sounds, even though they aren’t entirely conscious. Dormio tracks sleep stages to decipher when people are in hypnagogia, then it provides audio stimuli to keep them from falling into a deeper sleep.

Hypnagogia is the transition between wakefulness and sleep. During this state, it’s common to experience visual, audio, or other types of hallucinations. It’s also common to experience muscle jerks and sleep paralysis.

Some people purposefully try to induce to hypnagogia to stimulate creativity. Thomas Edison and Edgar Allan Poe are among the creatives who have used this technique.