This is a common hallucination that can occur in both healthy people and those with mental illness. It is thought to be caused by a combination of factors, including the way our brains process visual information and our expectations about the world around us.

2. Hearing voices

Auditory hallucinations, or hearing voices, are a common symptom of schizophrenia and other psychotic disorders. However, they can also occur in people with no mental illness, particularly during times of stress or sleep deprivation.

3. Feeling bugs crawling on your skin

This is a common hallucination that can occur in people with a variety of conditions, including schizophrenia, drug abuse, and delirium. It is thought to be caused by a combination of factors, including changes in the way the brain processes sensory information and the release of certain chemicals in the body.

4. Seeing geometric shapes

These hallucinations are often described as bright, moving geometric shapes that appear in front of the eyes. They are most commonly seen in people with epilepsy, but can also occur in people with other conditions, such as migraines, drug abuse, and sleep deprivation.

5. Experiencing a sense of déjà vu

This is a common experience that most people have at some point in their lives. It is thought to be caused by a temporary disruption in the brain's memory processing system, which causes us to feel like we have experienced something before when we actually haven't.

6. Having out-of-body experiences

These hallucinations are characterized by a sense of being separated from one's body, and can range from mild to intense. They are most commonly seen in people who have had traumatic experiences, such as near-death experiences, but can also occur in people with schizophrenia, drug abuse, and other conditions.

What do hallucinations tell us?

Hallucinations can be a sign of a variety of underlying conditions, including mental illness, drug abuse, sleep deprivation, and medical problems. However, they can also occur in healthy people, particularly during times of stress or high emotion.

If you are experiencing hallucinations, it is important to see a doctor to rule out any underlying medical conditions. Your doctor can also help you to determine if your hallucinations are a sign of a mental health problem, and recommend treatment if necessary.