0556 Prevalence and Incidence of Hypnagogic Hallucinations In A Longitudinal Study Of The American General Population

Abstract

Introduction: Hypnagogic hallucinations are vivid hallucinations that occur at sleep onset, during the transition between wakefulness and REM sleep. The hallucinations can be visual, auditory, tactile or kinetic and can be terrifying for the individual who experience them. Hypnagogic hallucinations are a common symptom of nar-colepsy, a disorder characterized by excessive sleepiness, cataplexy and disturbed sleep. The evolution of hypnagogic hallucinations remains seldomly investigated. There is no data regarding its incidence and its chronicity. This study examines the predictive factors for chronic hypnagogic hallucinations in the general population. Methods: This longitudinal study had two waves: 12,218 subjects interviewed by phone during wave 1 (W1); 10,931 during wave 2 (W2) three years later. The sample was representative of the general population based on US Census. Analyses included subjects participating to both waves (N=10,931). Logistic regression models were used to determine the predictive variables for persistent hypnagogic hallucinations. Results: At W1, 11.7% (95% CI:11.1%-12.3%) reported having experienced hypnagogic hallucinations in the previous year. At W2, 9.3% (95% CI: 8.8%-9.8%) reported hypnagogic hallucinations. A total of 22.8% of subjects with hypnagogic hallucinations at W1 still reported these hallucinations at W2 (2.1% of the sample). The 3-year incidence was 5.7% (95% CI: 5.3%-6.1%). After adjusting for age, sex, alcohol intake and medical conditions, persistence of hypnagogic hallucinations (i.e., present at both interviews) was predicted by the following factors: persistent pain (RR: 3.2 [95% CI:1.9-35.3] p<0.0001), persistent hypersomnolence (RR: 5.8 [95% CI:3.8-8.8] p<0.0001); persistent sleep paralysis (RR: 2.4 [95% CI:1.3-4.2] p=0.003); and persistent cataplexy-like symptoms (RR: 11.6 [95% CI:6.5-20.6] p<0.0001). Conclusion: Hypnagogic hallucinations are frequent in the general population. Its chronicity is predicted mostly by factors associated with narcolepsy such as hypersomnolence, cataplexy and sleep paralysis.