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The Hypnagogic State

The strange state of mind you pass through when first falling asleep is called the hypnagogic state. First studied by Baillarger in 1846 and named by Maury in 1848, hypnagogic phenomena have been experienced by about 70% of the adult population. Common hallucinations while falling asleep are faces and geometric patterns. Such hallucinations are not a sign of mental abnormality, although they can be startling if they appear unexpectedly.

What is the hypnagogic state? What hallucinations are common during this state?

Psychologist Thore Nielsen of Hospital du Sacre-Coeur in Montreal was interested in the hypnagogic state, so he trained himself to fall asleep at his computer. That way he could wake up when he had a hypnagogic hallucination and immediately record its content. He recorded 240 hallucinations this way. Most of the images involved movement. The most common recurring image was "falling or stepping out into space" (Adler, 1993). This could be a measurement effect: an effect on the data caused by the nature of the measurement. Going to sleep in front of his computer, Nielsen was in constant danger of losing muscle tone and falling to the floor, which might account for the repeated images of falling into space.

What causes hypnagogic imagery? The simplest assumption is that the hypnagogic state is an early-occurring dream fragment. This assumption is also consistent with reports that hypnagogic images are dreamlike. A subject in a 1930s experiment on hypnagogic imagery said, "These things [hypnagogic images] are practically dreams, but I am awake enough to catch them."

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