What is Hypnagogia?
Hypnagogia is a state of consciousness between wakefulness and sleep. It is the opposite of hypnopompia, a transitional state, which occurs after you wake up.
Hypnagogia belongs to the parasomnia group of disorders that occur as the person starts falling asleep. The hallucination seems like a vivid dream-like sensation and feels real. It can leave the person feeling afraid and disoriented.
During hypnagogia, a person experiences involuntary and imaginary experiences. These are known as hypnagogic hallucinations. In about 70 percent of people, these hallucinations appear in the form of sight, sound, and feeling of movement(1).
Hypnagogia is more common in teenagers and young adults and more in women than men.
How Does Hypnagogia Occur?
The neurons present in the brain communicate with each other through electrical activity burst. This electrical activity can be measured in waves with the help of electroencephalography (EEG).
EEG can measure five types of waves that are:
- Delta wave
- Theta wave
- Alpha wave
- Beta wave
- Gamma wave
When a person is awake the brain produces alpha and beta waves. Between both, beta waves are predominant. As a person gets drowsy, the alpha wave becomes predominant.
Stage one is the lightest form of sleep and lasts between 1 minute and 5 minutes. During this stage, the alpha wave drops to less than 50 percent of the total brain wave. The researchers in this stage observed ripples of slower theta waves(2).
Hypnagogia occurs in the period when the alpha waves are decreasing but have not reached the first stage. This is the transition phase. It is this period when you sense ‘here’ and ‘now’ transitions from the real world to the dream worlds. During this phase, a person experiences hallucination, lucid dreaming, body jerks, and sleep paralysis.
How Does Hypnagogia Affect The Body?
During hypnagogia, as the body enters sleep, it loses touch with reality. The effects experienced are:
1. Hypnaogic Hallucinations
Hypnagogic hallucinations are events that are imaginary but seem real. They occur at the time a person is falling asleep. These hallucinations are visual, auditory, or tactile.
It is commonly seen occurring in young adults and teenagers and gets less likely with age.
Though the cause of these hallucinations is not known, there are certain risk factors associated:
- Visual Hallucination
Visual stimuli are involved in about 86 percent of cases in hypnagogic hallucinations(3).
The ways in which visual hallucination manifests are:
- The appearance of random geometric patterns
- Flashing lights
- Kaleidoscopes of changing colors
- Images of people, animal, or faces
- Auditory hallucinations
Sounds are involved in 8-34 percent of hypnagogic hallucinations(4). The sound can range from hearing a faint sound to a loud crash or bangs.
The sounds may appear in the form of:
- Words or voices
- Doorbell sound
- Phone ringing
- Your name
- Other hallucinations
Around 24-44 percent of people may report the following feelings(5):
- A feeling of presence in the room
2. Tetris Effect
Tetris effect is a phenomenon that involves intrusive images or thoughts entering your mind when a repetitive activity is performed.
The name of this effect is derived from the video game ‘Tetris’.
The game activates visuomotor processes in the part of the brain involved in coordinating movements and visual perceptions. As these processes get activated, a person can have hypnagogic hallucinations where the shapes from the video game are seen before falling asleep.
3. Hypnogogic Jerks
Sudden muscular contraction on falling asleep is known as a hypnogogic jerk. This leads to sudden and strong contractions of muscles that may wake you up from sleep.
These jerks are known to affect 60-70 percent of people(6).
4. Sleep Paralysis
The feeling of being awake but not being able to move is known as sleep paralysis. It is seen occurring in people with narcolepsy along with hypnogogic hallucinations.
Sleep paralysis can be really frightening but the symptoms go away in a minute or so without any health consequence.
5. Lucid Dreams
It is called lucid dreaming when a person is dreaming and he tries to control the dream or the storyline.
Some people even try to lucid dream to stimulate creativity.
Hypnagogia is a transition between sleep and wakefulness in which people experience visual, audio and other types of hallucinations. Muscle jerks and sleep paralysis are commonly experienced in it. Some try to purposefully induce it to stimulate creativity.