Hallucinations, as the name suggests, delves into various clinical case studies where people “see” things that don’t exist projected onto reality. Oliver Sacks discusses different mental conditions and the types of hallucinations patients experience, such as those associated with Charles Bonnet syndrome, Parkinson’s disease, and epilepsy. The book also includes discussions of auditory (hearing things that don’t exist) and olfactory hallucinations (smelling things that don’t exist).

Oliver also talks about cases where hallucinations occur in sane people, such as on the threshold of sleep (hypnagogic hallucinations) or just as people rise from sleep (hypnopompic hallucinations). Apart from these, the book covers other fascinating cases like doppelganger hallucinations (where you hallucinate another person just like you) and out-of-body experiences (OBE) where one feels oneself outside of their body.

The writing is quite enjoyable. Occasionally, you might find yourself bored with the motifs in certain chapters. However, an equal number of times, you come across something truly exciting like an interesting literary reference or a spine-chilling case. For example, consider the following case:

Once, a patient diagnosed and treated by Oliver, rushed to him and questioned why Oliver, whom he considered a nice guy, asked him to jump off the hospital roof. Oliver asked the man if he had seen him around, to which the man replied, “No.” Oliver suggested that the next time he hears such a voice, he should look around and check. The next day, the man again heard Oliver’s voice commanding him to jump off the roof, adding, “And no need to turn around, because I am already here.” Fortunately, the man resisted the urge to jump, and after three years of treatment, he eventually recovered.

Oliver is also an avid reader and frequently points out popular literature references. Dostoevsky had temporal lobe epilepsy, and it has been observed that people with this condition often have hyper religiosity. I often used to wonder why a rational thinker like Dostoevsky would be so religious. It is a strange realization to learn that the style of his writings may have originated from a physiological dysfunction. Another interesting fact for literary enthusiasts - Guy de Maupassant experienced doppelgänger hallucinations, a phenomenon where you hallucinate someone who looks exactly like you.

Paranormal experiences have neurophysiological origins

Whenever I hear a paranormal story from any of my friends, I wonder about the true rational explanation behind it. I strongly believe that nothing is supernatural and that everything adheres to the laws of physics. This book aims to strengthen such convictions in others as well. Throughout the book, we come across cases where patients experience seemingly paranormal events, such as encountering someone who looks exactly like themselves or hearing a voice just after waking up. In cultures that lack scientific or rational understanding, these experiences often give rise to tales of ghosts and spirits. Realizing that these phenomena have a physiological basis can enlighten many of us.

Favourite part

In conclusion, I would like to highlight my favorite part of the book - the chapter titled “Altered States.” This chapter was particularly enjoyable for me, as the stories were incredibly trippy. The last story, however, was truly moving. During a period in Oliver’s life, he had a routine of spending weekends under the influence of amphetamines. These dangerous drugs can lead to high blood pressure, and overdoses, which are all too common, can be fatal. After each weekend, Oliver would feel drained and guilty.

Once, he happen to come across a book on Migranes by Edward Levine. A fat book of around 500 pages written in 1860s. On amphetamines, as he read the book, the emotions because intensified. He felt as though he was writing it, he was living the book. Oliver was really fascinated by Edward’s writing, which had a perfect mixture of science and humanism. He read the book in one go straight without moving a muscle. After done with reading, Oliver asked himself who would be Edward of his era. An inner voice answered “you”. Oliver, then decided to start writing his own book. As he describes, the joy he derived from writing the book was infinitely real. The story ends with the line And I never took amphetamines again.

Once, he came across a book on migraines by Edward Liveing, a hefty book around 500 pages on migrane, written in1870s. One weekend, while on amphetamines, as he read the book, his emotions intensified. He felt as though he was writing it and living the book. Oliver was deeply captivated by Edward’s writing, which masterfully combined science and humanism. He read the book in one sitting without moving a muscle. When he finished reading, Oliver asked himself who would be the Edward Liveing of his time. An inner voice replied, “You silly bugger! You are the man.”. This prompted Oliver to start writing his own book. As he describes, the joy he derived from writing the book was infinitely real. The story concludes with the line, And I never took amphetamines again.

Once, he came across a substantial volume of around 500 pages on migraines, written by Edward Liveing the 1870s. One weekend, while on amphetamines, as he read the book, his emotions intensified. He felt as though he was writing it and living the book. He felt as if he was becoming Liveing himself, seeing the patients he described in the book. Oliver was deeply captivated by Liveing’s writing, which masterfully combined science and humanism. He read the entire book in one sitting, without moving a muscle. When he finished reading, Oliver asked himself who would be the Edward Liveing of his time. An inner voice responded, “You silly bugger! You are the man.”. This prompted Oliver to start writing his own book. As he describes, the joy he derived from writing the book was infinitely real. The story concludes with the line, And I never took amphetamines again

Certain drugs can amplify emotions, and what I find remarkable about this story is that Oliver found a greater sense of purpose in life while on amphetamines, which in turn led him to leave amphetamines behind. This contrasts with the common perception that the more substances are an escape from reality. While this may be true in many cases, this story demonstrates that an amplified emotional state, when combined with the right setting - such as reading a book on a subject you deeply care about - can reveal a hidden potential within.

I have always been captivated by the diverse experiences that the human brain can generate, and this book offers a plethora of such instances. On a personal level, this book has reinforced my belief that ultimately the underlying physiology dictates an individual’s experiences and behaviours.