Hypnagogic Hallucinations

On CL, we frequently get consulted for new-onset hallucinations. Often, we find that these are due to delirium. However, there is a subset of patients who have something called hypnagogic hallucinations. Here is a brief overview:

Hypnagogic Hallucinations

Definition: Hallucinations at sleep onset (during transition from wake to sleep)

    -Due to a REM intrusion into wakefulness

Epidemiology

• Can occur in healthy individuals without comorbid conditions (25-40% lifetime prevalence)
• Also commonly in narcolepsy (20-60% of patients with narcolepsy)
• Other conditions:
  • Sleep disorders
    • Insomnia/sleep deprivation
    • OSA
  • Psychiatric
    • PTSD
    • Anxiety
    • MDD
  • Substance
    • Withdrawal states
    • Medication side effect (SSRI (early in treatment, see below, they are also a treatment when used long-term), dopaminergic meds)
    • Hallucinogens
  • Neurologic
    • Parkinson disease
    • Lewy body dementia

Severity

-Most cases are benign and insight is preserved. There is no daytime psychosis.

-It’s more concerning when hallucinations also occur during full wakefulness, there is no insight, or there are other psychotic or neurologic symptoms.

Phenomenology

–Visual most common (people, shadows, figures)

–Auditory: Less common (voices, sounds)

–Tactile: “presence” of someone in room, being touched

Often vivid, dream-like, brief, emotionally intense.

Stepwise Management

-Step 1: Reassurance + education (often sufficient)

-Step 2: Optimize sleep

    -sleep hygiene, regular schedule, limit caffeine/alcohol

-Step 3: Rule out sleep disorders

    -especially narcolepsy

Pharmacologic Treatment

• Antipsychotics NOT indicated
  • Wrong mechanism (not due to dopamine, but rather REM intrusion)
  • Can worsen parasomnias
• If distressing, first line:
  • SSRI/SNRI (REM suppression)
• Alternatives:
  • Low dose TCA (clomipramine)
  • Clonazepam (use with caution)
  • Melatonin