Seeing things as you fall asleep? It’s a known phenomenon—here’s why.

Seeing things as you drift off to sleep—known medically as hypnagogic hallucinations—is surprisingly common. Most people experience brief, dreamlike images, sounds, or sensations just as they’re nodding off. While usually harmless, these “hallucinations when falling asleep” can feel unsettling. This guide explains why they happen, when they’re normal, and when to seek help.

What are hypnagogic hallucinations?
Hypnagogic hallucinations occur at the transition from wakefulness to sleep. They differ from full-blown psychotic hallucinations in key ways:

• They’re brief (seconds to a minute)
• They often involve simple shapes, flashes of light, or snippets of sound or conversation
• They occur alone or in combination with sleep-onset muscle twitches (hypnic jerks)

Why do they happen?
Sleep involves shifting brain states. Hypnagogic hallucinations stem from a temporary overlap between wakefulness and REM (rapid eye movement) sleep, the dreaming phase. Key factors:

• REM sleep intrusion
– Normally, REM is confined to deep sleep. In some people, REM brain activity “leaks” into wakefulness just as they fall asleep.
– This mixture of dream-state imagery with consciousness produces vivid, dreamlike perceptions.
– Intrusions of REM mechanisms explain why people with narcolepsy often report hypnagogic hallucinations (Dauvilliers et al., 2007).

• Neurotransmitter imbalance
– Chemicals like serotonin, dopamine, and hypocretin (orexin) regulate sleep–wake transitions.
– Disruptions in these systems can make sleep-onset boundaries fuzzy, increasing hallucination risk.

• Sleep deprivation and irregular schedules
– Lack of sleep makes REM onset occur faster and more unpredictably.
– Shift-work, jet lag, or all-nighters can trigger more frequent sleep-onset hallucinations.

Other contributing factors

• Stress and anxiety: High stress can fragment sleep and blur wake–sleep boundaries.
• Medications and substances: Antidepressants, stimulants, or withdrawal from alcohol and sedatives may alter sleep architecture.
• Mental health conditions: Depression, PTSD, or schizophrenia can feature sleep-related hallucinations, though these are often more severe.

When are they just benign?
Most people have harmless hypnagogic hallucinations occasionally, especially when:

• You’re extremely tired or sleep-deprived
• You’ve had a major schedule change (travel, new job shift)
• You experience them infrequently and without distress

What about more serious causes?
In rare cases, hallucinations when falling asleep can signal an underlying condition:

1. Narcolepsy with cataplexy
   – In narcolepsy, people can experience excessive daytime sleepiness, sudden muscle weakness (cataplexy), and vivid hypnagogic or hypnopompic hallucinations.
   – Dauvilliers et al. (2007) note that up to 50% of narcolepsy patients report these phenomena.

2. Hepatic encephalopathy
   – Advanced liver disease can lead to toxin buildup affecting brain function, sometimes causing visual or auditory hallucinations.
   – According to EASL clinical practice guidelines (2015) and Schuppan & Afdhal (2008), cirrhosis patients with confusion or hallucinations need prompt evaluation for hepatic encephalopathy.

3. Other neurological conditions
   – Parkinson’s disease, Lewy body dementia, and certain brain injuries can produce vivid hallucinations, though these usually occur while fully awake.

When to seek professional advice
See a healthcare provider if you experience:

• Frequent or worsening sleep-onset hallucinations
• Distressing or terrifying images that disrupt falling asleep
• Daytime sleepiness, cataplexy (sudden muscle weakness), or sleep paralysis
• Signs of liver disease (confusion, jaundice, swelling) alongside hallucinations

You may also consider doing a free, online symptom check for more immediate guidance on your specific experiences.

Tips to reduce sleep-onset hallucinations
Improving overall sleep hygiene and managing stress can often help:

• Keep a consistent sleep schedule
– Go to bed and wake up at the same times daily, even on weekends.

• Create a calming pre-sleep routine
– Avoid screens, bright lights, and stimulating activities for at least 30 minutes before bed.
– Try reading, gentle stretching, or deep-breathing exercises.

• Optimize your sleep environment
– Make your bedroom cool, dark, and quiet.
– Use comfortable bedding and limit noise.

• Limit caffeine and alcohol
– Avoid caffeine late in the day; alcohol can fragment sleep and worsen REM intrusion.

• Manage stress and anxiety
– Practice mindfulness, meditation, or journaling to process worries before bedtime.

• Get regular exercise
– Aim for at least 150 minutes of moderate activity per week, but finish workouts at least a few hours before bed.

When lifestyle changes aren’t enough
If hallucinations persist or worsen despite good sleep habits, talk with a healthcare professional. They may:

• Review your medication list for any that affect sleep architecture
• Order sleep studies (polysomnography) to check for narcolepsy or other sleep disorders
• Evaluate for liver or neurological conditions if other symptoms are present
• Consider short-term sleep aids or targeted therapies under medical supervision

Remember, occasional hypnagogic hallucinations are common and typically harmless. But if they’re frequent, distressing, or paired with other symptoms like excessive daytime sleepiness or confusion, it’s important to get evaluated.

Speak to a doctor about anything that could be life-threatening or serious, such as sudden confusion, severe daytime impairment, or signs of liver disease. A prompt professional assessment ensures you get the correct diagnosis and treatment plan.

By understanding the mechanisms behind “hallucinations when falling asleep,” adopting good sleep practices, and knowing when to seek help, you can reduce their impact on your life and rest easier.