Hypnagogic Hallucinations


Hypnagogic hallucinations can occur at sleep onset, either during daytime sleep episodes or at night. They are usually quite vivid, and often involve vision. The visual hallucinations usually consist of simple forms colored circles or parts of objects that are constant or changing in size. People may also see the image of an animal or a person, and are more often in color. Auditory hallucinations are also common, but other senses are seldom involved. The auditory hallucinations can range from a collection of sounds to an elaborate melody. Threatening sentences or harsh criticism might also menace the person. Another common and interesting type of hallucination that is sometimes reported at sleep onset involves elementary cenesthopathic feelings (like experiencing picking, rubbing, or light touching), changes in location of body parts (like an arm or a leg), or feelings of levitation or extracorporeal experiences (like moving the body in space or floating above the bed) that may be quite elaborate. The association of sleep paralysis has led researchers to think that maybe there was gamma loop involvement in some of these hallucinations. The abrupt motor inhibition that involves the spinal cord motoneurons may lead to a significant decrease in the feedback of information normally used by the central nervous system to gauge the position of the body and the relation of the limb segments to each other (this information is called proprioception).

The painting (marbling on polygraph paper) at the top of this page is titled 'Hypnagogic Tease', and is part of a series of works called 'One Night of Sleep and Dreaming' by artist Fariba Bogzaran.

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