The hypnagogic state is the condition which exists between being awake and sleeping. For some people, this is a time of sensory hallucination, consisting of illusions of vision and sound.

A hypnagogic state occurs at the onset of sleep before entering into REM. It is associated with vivid, sometimes bizarre, hallucinatory imagery. It is thought that hypnagogic mentation is a greatly diminished version of REM sleep, but by avoiding the narrative and emotional complexity of REM dreams and instead loosening the usual restrictions upon thought, it allows one to survey the contents of his or her subconscious. Thus, one experiences at the level of awareness the creative mental processes which usually stir in the depths of the unconscious.

During the hypnagogic state, there is a decrease in normal thoughts and an increase in unusual, more dreamlike thoughts. People can experience brief and vivid imagery or sensations in one or more different sensory modalities. Many people who engage in new physical or mental activities for extended periods of time often experience a hallucinatory replay of the activities as they fall asleep.


"Auditory hypnagogic phenomena include the hearing of crashing noises, one's name being called, a doorbell ringing, neologisms [new words or expressions], irrelevant sentences containing unrecognizable names, references to spoken conversations, remarks directed to oneself, meaningful responses to one's thought of the moment." (Mavromatis, 1987)

The hypnagogic speech phenomenon occurs when a person hears him/herself uttering words, which can be nonsensical or irrelevant, just as they are falling asleep.

Other reported sensory illusions include music, bangs and explosions. Inaccurate time perception, sensations of smell or taste, sensations of actively touching or being touched by someone or something, and hot or cold sensations, sometimes moving along the body, have also been reported during the hypnagogic state.

Sleep starts, which are sudden brief muscle contractions in one or more parts of the body which occur at sleep onset, are another feature of hypnagogia. Sleep starts are sometimes associated with hypnagogic imagery, such as illusory sensations of movement or auditory phenomena (examples listed above). A sensation of falling seems to be the most commonly reported sensation of movement. The experience is often associated with a bodily jerk and visual imagery, such as falling off of a cliff. Other sensations of movement may include floating, swinging, rocking, spinning, and being in or on a moving vehicle. Bodily sensations may include, for example, weightlessness, heaviness, tingling, numbness, shaking or vibrating, and elongation of the body. A sense of presence has also been reported and may coincide with both imagery and sleep paralysis.


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The basic stages of sleep, by convention, are divided into two main types: REM (Rapid Eye Movement, or dreaming) and Non-REM (NREM).

NREM generally is broken into four stages: 1, 2, 3, and 4. In each stage, brain waves become progressively larger and slower, and sleep becomes deeper. After reaching stage 4, the deepest period, the pattern reverses, and sleep becomes progressively lighter until REM sleep, the most active period, occurs. This cycle typically occurs about once every 90 minutes in humans. About 75% of total sleep is spent in non-REM and 25% in REM.

Beta waves - (very low amplitude, high frequency; 13 to 30 waves/sec) A person is awake and active (in a state of alertness). They are the fastest [EEG] waves and signal an active cortex and an intense state of attention.

Alpha waves - (low amplitude, 8 to 13 waves/sec) A person is awake and relaxed, with closed eyes. Neurons are firing at different times.

Theta waves - (low-medium amplitude, spike-like waves; 3-7 waves/sec) A person is sleepy, already sleeping, or in a sleep transition. This is the stage during which hynagogic phenomena most commonly occurs.

Delta waves - (high amplitude, low frequency; 3 waves/sec) A person is deep asleep. Neurons, which are not engaged in the processing of information, are firing all at the same time. Therefore, the activity is synchronized. Waves are large and slow.

REM - (60 to 70 waves/sec) Maximal retraction of the pupil and nictating membrane follow the volleys of ocular movements (i.e. watching the things taking place in one's dreams).