photo of a woman in bed experiencing hypnagogic hallucinations

Do strange images of geometric shapes, people or animals appear out of nowhere as you lie in bed at night? Perhaps you’ve heard voices or noises which can’t possibly be real?

If so, it could be that you’ve experienced what’s known as sleep hallucinations.

Despite leading to the occasional leap out of bed in sheer terror, they are usually harmless. And many people experience them at some point in their lives – including me.

My nocturnal flying geometric manifestations

As a child, multicolored geometric shapes would regularly swoop across my bedroom, just as I thought I was drifting off to sleep. I remember simultaneously marveling at them and wishing them away so I could sleep in peace.

It doesn’t happen so often nowadays, but once in a while, I’m still prone to my mathematical manifestations.

Perhaps I should be grateful for my geeky hallucinations – especially compared to the disturbing experiences some people have.


What are sleep hallucinations?

Sleep hallucinations are imaginary experiences that happen during the transition between being awake and asleep, and can feel confusingly real.

They are also referred to as hypnagogic hallucinations if they occur while you’re falling asleep, or hypnopompic hallucinations if they happen while waking up.

The hallucinations are usually visual, such as seeing shapes or figures in the dark. But they can also involve your other senses.

The hallucinations can be vivid and frightening in some cases. If you see a giant creature in your room or hear a scary voice, it’s understandable that some people will jump out of bed and turn the light on to check what’s going on!

image explaining that hypagogic hallucinations occur while falling asleep and hypnopompic hallucinations while waking up

How many people have sleep hallucinations?

A commonly quoted statistic in medical articles comes from research conducted in 1996. The team interviewed 4972 people in the United Kingdom by telephone. They found that 37% had experienced hypnagogic hallucinations. And 12.5% had experienced hypnopompic hallucinations.

In 2000, another team of researchers surveyed 13,057 people and found that 38.7% had experienced hallucinations at some point during the day or night. 24.8% of the sample had experienced hallucinations at sleep onset, and 6.6% upon waking.

A sign of Narcolepsy

For some people, sleep hallucinations can be a sign of narcolepsy. Narcolepsy is a sleep disorder which involves sudden daytime episodes of:

  • Unexpectedly falling asleep
  • Sleep paralysis
  • Hypnagogic hallucinations

If you have these symptoms, it’s important to seek medical advice.


Symptoms


The main symptom is imagining events while falling asleep or waking up that are not real. Researchers believe that the most common type of hallucination is visual.

However, it’s possible to experience hallucinations that correspond to any of your senses:

  • Visual – such as geometric patterns, shapes or light flashing. Sometimes complex forms like animals or people.
  • Auditory – voices talking, phone or doorbell ringing, music, hissing, humming or whistling.
  • Olfactory – pleasant or unpleasant smells.
  • Tactile – insects crawling on the skin, rubbing, stroking, tapping or tickling sensations. Perhaps also feeling weightless, distortions in the body, flying.
image of a woman in bed with patterns and animal forms around her

Not the same as nightmares

Telling the difference between dreaming and hallucinating isn’t always obvious in the moment. But sleep hallucinations are not the same as nightmares.

When you wake up from a nightmare, you’ll know you were asleep (even if it takes a little while to come back to reality).

Sleep hallucinations, however, can feel like they are really happening. You know you’re awake, but you’re not convinced it’s merely your imagination playing tricks on you.

Coexisting with sleep paralysis

Sleep hallucinations sometimes happen during an episode of sleep paralysis.

During sleep paralysis, you might be unable to move your body in bed, which in itself is often frightening.

The hallucinations that accompany it can range from seeing a presence in the room to seeing and feeling a creature sitting on you.


Causes


The International Classification of Sleep Disorders manual suggests two causes related to brain function, though also states that more research is needed:

  • An intrusion of dream imagery onto wakefulness.
  • A lack of stimulus leading to the visual cortex in the brain creating images.

Health websites, such as healthline.com, suggest that sleep hallucinations can be caused by other conditions, such as:

  • Sleep disorders like narcolepsy or sleep paralysis
  • A medical condition or medication use
  • A mental health disorder, such as schizophrenia
  • Substance abuse

Risk factors

According to the American Academy of Sleep Medicine, they are more common in children and young adults. Women might experience them slightly more often than men.

Some factors are thought to increase the likelihood or severity of the hallucinations, including:

  • Drug or alcohol use
  • Anxiety or stress
  • Mood disorders like bipolar disorder or depression
  • Insomnia
  • Epileptic seizures

Treatment


Do you need to see a doctor?

If you’re experiencing anxiety or losing sleep because of regular sleep hallucinations, it’s a good idea to speak to a doctor or sleep specialist.

They would ask you about your hallucinations and look at your medical history and other factors like medication and lifestyle. They might decide that an overnight sleep study is needed to find out more.

They would also look at the possibility of another condition causing the episodes. And if they find one, give you the appropriate treatment.

What can you do to help reduce them?

Here are some ideas which might help keep the hallucinations at bay:

  • Get an adequate amount of sleep every night. Try to stick to a regular sleep schedule and don’t allow yourself to become sleep deprived.
  • Avoid recreational drugs.
  • Eat a healthy diet and drink plenty of water.
  • Try to reduce your stress levels.
  • Try using a soft night light in the bedroom. This might help fill the space that your brain uses as a blank canvas.
  • If you tend to hear sounds that are not real, perhaps listening to music or the radio at night will help.
  • If you find yourself focusing on visual hallucinations, try to re-focus your mind on something else. Breathing exercises or muscle relaxation can keep your brain occupied.
  • If it’s overwhelming, turn on a light and get up for a while, do an activity you find relaxing and then try to sleep again after 10-15 minutes.
  • Several readers have said in the comments below that wearing a sleep mask helps them.

Generally though, you can see that hypnagogic and hypnopompic hallucinations are a normal part of life for many people. Once you’ve ruled out any serious illness or disorder, you’re left to deal with the experience in two ways.

First, try to adapt your lifestyle to make sure you do everything possible to sleep well. Second, relax and try not to worry about things that go bump in the night.

Your thoughts

Do you ever experience hallucinations when falling asleep or waking up? What form do they take?

Feel free to describe your experience in the comments below and share any ideas you have about dealing with them.

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