Sleep related hallucinations

Sleep- related hallucinations, in community studies, are said to be fairly common. Over 25% of people are supposed to have experienced hypnagogic hallucinations (hallucinations at sleep onset), with fewer (perhaps around 10%) having experienced hypnopompic hallucinations (around the time of waking).

I ask for this symptom reasonably frequently. In my experience it is rare.

This symptom is part of the narcoleptic tetrad; about 60% of narcoleptics with cataplexy, and about 30% of 'narcoleptics without cataplexy' suffer.

Perhaps because of the association with narcolepsy, sleep-related hallucinations are believed to represent REM sleep intruding into wakefulness. The visual hallucinations are often vague and indistinct. Perhaps part of the reason that there are reports which suggest high prevalence is that very simple visual disturbances, such as points of light or the perception of shape patterns while eyes are closed, might also be regarded as hallucinations.

Reassurance may be all that is required, unless there is associated narcolepsy. Tricyclic antidepressants are often prescribed, particularly in narcolepsy, for this problem. However, data on their efficacy is lacking. (Gamma-hydroxybutyrate is also used in narcolepsy for this purpose, but I am not aware that this drucg is available in Australia other than illicitly. Suppression of REM sleep may be the mode of beneficial action of these medications).

Andrew