Hypnagogic and hypnopompic hallucinations: pathological phenomena?
The British journal of psychiatry : the journal of mental science October 1, 1996 M M Ohayon, R G Priest, M Caulet et al.
In a representative UK community sample of 4,972 people aged 15-100 interviewed by telephone, 37% reported hypnagogic hallucinations (occurring when falling asleep) and 12.5% reported hypnopompic hallucinations (occurring when waking up). Both types were more common among those with insomnia, excessive daytime sleepiness, or mental disorders. The prevalence of narcolepsy in the UK was 0.04%. Hypnagogic and hypnopompic hallucinations were much more common than expected, far exceeding what narcolepsy alone can explain. Hypnopompic hallucinations may be a better indicator of narcolepsy in people reporting excessive daytime sleepiness.