The British Journal of Psychiatry comments that hypnogogic hallucinations - vivid perceptual experiences occurring at sleep onset - are far more common than expected. Around 12.5 per cent of people also experience hypnopomic hallucinations which occur on awakening.
In both cases, the feeling of falling into an abyss was most common, followed by the feeling that someone or something was in the room. Other hallucinations included the sensation of flying, seeing moving or distorted objects, and being caught in a fire. Glenda CooperReuse content