How do hallucinations happen? They are caused by a chemical imbalance or some kind of abnormality in the brain.
All hallucinations are created by the sensory parts of our brain and they are basically firing without the stimulus. If you look at a dog, light is bouncing off the dog and entering your eyes. Your eyes convert that light into an electrical signal that is passed to the brain and the brain analyzes the signal, translating it into an object. A hallucination happens in the same way except there is no dog and no light is entering the eye or being passed to the brain. The brain reacts as though a signal is arriving, and translates that into an image. Hallucinations are very real because the part of our brain that senses real things is creating them and it is difficult to disbelieve our own brains.
There are several different types of hallucination. Basically, every sense that we have can cause a hallucination. We have auditory hallucinations when we hear someone talking or hear sounds. Visual hallucinations when we see something that isn’t there. Tactile hallucinations when we feel like we are being touched. Olfactory hallucinations when we smell something that isn’t real. Gustatory hallucinations when we experience strange tastes without eating anything. Presence hallucinations when we feel that someone is in the room. Proprioceptive hallucinations when we feel like we are flying. There are also a few hallucinations that can happen while we are asleep and be a part of sleep paralysis.
General hallucinations are more common than we might think. We have all experienced hallucinations such as phantom phone. That is when you keep your phone in your pocket and you feel it vibrate, take it out to check the text, and there is nothing. Hallucinations like this are probably caused by too much stimulation. We get so many texts on our phones that we start to expect them and our brain becomes hyperaware of them. Then, possibly, we move in such a way that our clothes rub, or a muscle simply twitches, and the brain interprets it as a phone vibration. These kinds of hallucinations are just a mind that is too stimulated.
Often, different types of hallucination have different causes, but not all of the causes are actually known. There are two interesting theories about how auditory and visual hallucinations manifest themselves. Auditory hallucinations are when you think you have heard something, usually a voice, that isn’t there. This is a big part of mental illnesses such as schizophrenia. The theory is that the voice people hear is actually their own inner speech. We all talk to ourselves in our heads all of the time. We have an inner voice that speaks a lot of our thoughts to us. When we speak out loud, the brain has to send signals to move the lips, tongue, vocal cords, and facial muscles in order to produce the speech. The brain needs to know that the movements it is making are producing the desired speech, so it needs a method to check. This method is called an efference copy. The same happens when we move our arms. The brain has to check that the arm movement matches the signal that was sent. With speech, the brain sends the signal to the lips, tongue, and vocal cords, it also sends a copy of the signal to the part of the brain that processes sound. When we hear ourselves speak, the sound processing part of the brain compares the sounds it is hearing with the efference copy and makes sure that they match. Experiments have shown that our inner voice, the one we use when we think, also produces an efference copy. One theory on why people with schizophrenia here voices is because they lack the ability to make an efference copy. We use it to check our movements, but we also it to know what stimuli has been caused by our movement and what stimuli has been caused by external movement. Without the ability to make an efference copy, all stimuli appear to be external, including the voice in our head and many movements. It will appear as though something or someone else is making the person with schizophrenia move or is speaking in their head.
A theory for some visual hallucinations is that they are caused by the neurons in the brain actually slowing down. Experiments with mice showed that when they were injected with a hallucinogenic chemical, the parts of their brains concerned with vision slowed down and fewer neurons fired. The brain is still taking in information but isn’t able to interpret it properly, leading to hallucinations.
There are many causes for the different types of hallucinations and tiredness can even cause them. Sleep deprivation has been known to cause hallucinations, but no one knows exactly why. It could be because parts of the brain get disrupted, it could be because of chemical buildup, it might be because there is too much dopamine in the brain. Generally, though, people who hallucination because of causes like sleep deprivation logically know that they are hallucinating. People who experience them because of mental illness or brain damage don’t know that they are hallucinating. And this is what I learned today.
Photo by cottonbro studio: https://www.pexels.com/photo/woman-in-brown-coat-sitting-beside-man-in-black-coat-6763604/
Sources
https://www.self.com/story/sleep-deprivation-hallucinations
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https://www.frontiersin.org/articles/10.3389/fnsys.2021.765646/full
https://dermnetnz.org/topics/phantom-vibration-syndrome
https://en.wikipedia.org/wiki/Efference_copy
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https://www.healthline.com/health/hallucinations
https://en.wikipedia.org/wiki/Hallucination
https://www.medicalnewstoday.com/articles/327014
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2702442/