Hypnagogic hallucinations

How it works

Hypnagogic means “leading into sleep”. Hypnopompic means “leading out of sleep”¹². The shift between waking and sleep is a state of its own¹. One idea is that parts of dreaming (REM) sleep appear early, while the brain is still partly awake¹. Dream content gets mixed in with real sight and sound.

The common experiences are geometric patterns and images of real things; hearing your name, a doorbell, or a voice; and a feeling of falling or floating¹. Touch and, more rarely, music can also occur¹. After hours of a repeated task such as a video game, you may see it replay as you fall asleep. This is called the Tetris effect³.

They often go together with sleep paralysis.

How common it is

The 25% to 37% range comes from two large telephone surveys that asked people to recall past experiences⁵⁶. Brief, mild versions are easy to forget by morning, so the real share of people who have them is probably higher than surveys catch. They are more common in people with insomnia or excessive daytime sleepiness⁵.

Is it a problem?

No. On their own, they are usually not a sign of mental illness⁶. Hearing your name once at the edge of sleep is a normal brain doing a normal thing. They need no treatment.

See a doctor if hallucinations:

• happen while you are fully awake during the day,
• come with sudden weakness when you laugh,
• come with attacks of sleep you cannot resist.

That pattern can be narcolepsy, which is treatable⁴. Also mention them to a doctor if they start after a new medicine.

History and culture

The painter Salvador Dalí and the inventor Thomas Edison both said this state helped their creative work¹.