Hypnopompic hallucinations are often discussed along with hypnogogic hallucinations. Both of these have to do with hallucinations occurring as people enter or exit sleep. When people are just on the edge of sleep they might experience hypnogogic hallucinations. If a person is about to wake, he or she could have a hypnopompic hallucination.
What makes hypnogogic and hypnopompic hallucinations different from dreams is that they tend to lack a story. Moreover the hallucinations may vary. People could experience a physical feeling, a smell, a sound, or quite frequently an image or sight.
The image could be a simple line, dot, pattern, or it could be a full person, animal or other. It is important to add that whatever experienced, the perception of something not there can feel very real. Hypnopompic hallucinations might make people bolt out of bed, and then feel very disoriented, or they sometimes create the sensation that the person is paralyzed and cannot move.
Hypnogogic and hypnopompic hallucinations are characterized by their “realness.” They also have a tendency to disrupt sleep. While they might suggest a person has sleep disorder, the hallucinations do not have much to say about the sanity of the person having them.
In most instances these forms of hallucinations are associated with other sleep disorders, and often particularly with inability to get to sleep. This isn’t always the case. An interesting survey study done in the last decade of the 20th century collected data from a number of people to compare how often people reported hypnogogic and hypnopompic hallucinations. Data of nearly 5000 respondents showed that quite a few people had had at least one incidence of either of these sleep or waking disturbances.
As published in the British Journal of Psychiatry, over 12 % of the people surveyed experienced hypnopompic hallucinations and close to 40% had had hallucinations when falling asleep at night. A conclusion that can be drawn from the study is that of the two types of hallucinations clearly hypnogogic sensations are more common. Another suggestion made by the authors of the study was that hallucinations occurring just before waking were more likely to happen if people did have a sleep disorder.
This last conclusion is perhaps important because frequent episodes of hypnopompic hallucinations may suggest poor sleep or sleep disorders that could be remedied. Yet, people may definitely fear discussing this issue with a doctor because they might believe a doctor will look at them askance. As previously mentioned, neither of these types of hallucinations indicates mental instability, and there is plenty of medical literature to back this up. On the other hand, such hallucinations really can suggest poor sleeping habits, and that can be dangerous to health on a number of levels.