Hypnagogic and Hypnopompic Hallucinations: Pathological Phenomena?

TLDR

Hypnagogic and hypnopompic hallucinations are common in narcolepsy, yet their prevalence in the general population is uncertain. A representative UK community sample of 4,972 adults aged 15–100 was interviewed by telephone using a computerised system guided by lay interviewers. The study found that 37 % reported hypnagogic and 12.5 % hypnopompic hallucinations, with both more frequent among those with insomnia, daytime sleepiness or mental disorders, indicating that these hallucinations are far more common than narcolepsy alone would predict and that hypnopompic events may better signal narcolepsy.

Abstract

Background Hypnagogic and hypnopompic hallucinations are common in narcolepsy. However, the prevalence of these phenomena in the general population is uncertain. Method A representative community sample of 4972 people in the UK, aged 15–100, was interviewed by telephone (79.6% of those contacted). Interviews were performed by lay interviewers using a computerised system that guided the interviewer through the interview process. Results Thirty-seven per cent of the sample reported experiencing hypnagogic hallucinations and 12.5% reported hypnopompic hallucinations. Both types of hallucinations were significantly more common among subjects with symptoms of insomnia, excessive daytime sleepiness or mental disorders. According to this study, the prevalence of narcolepsy in the UK is 0.04%. Conclusions Hypnagogic and hypnopompic hallucinations were much more common than expected, with a prevalence that far exceeds that which can be explained by the association with narcolepsy. Hypnopompic hallucinations may be a better indicator of narcolepsy than hypnagogic hallucinations in subjects reporting excessive daytime sleepiness.