Book Review: Hallucinations by Oliver Sacks

Over the holiday break I got caught up on some reading, including Oliver Sacks new book “Hallucinations” Did Sacks deliver a mind-bending or mind-numbing account of the powerful hallucinations the human brain can conjure up?

I had never read any of Oliver Sacks book’s before, but I had heard good things about his previous works like The Man Who Mistook His Wife for a Hat and Musicophilia. Additionally, I do have a strong interest in the subject matter of hallucinations and weird things the brain does, so this book was high on my Christmas list this year. Even while wandering through the book store at UBC I always had to stop and flip through the book every time I passed it.


Sacks is a neurologist at the NYU School of Medicine and a popular science writer. Based on his qualifications, he’s an expert guide for a journey of hallucinations.

The first thing I noticed was the affluent amounts of wit, charm, and easiness with which Sacks explains the complicated and sometimes frightening way in which hallucinations work. The language is both accessible, detailed and reads pleasantly. As someone with no background in neurology (the most I know about the brain is not to poke it with a Q-tip) I found the text remarkably clear and easy to follow.

The book is divided into fifteen chapters and each chapter focuses on a different type of hallucination. In the first chapter Sacks explains the hallucinations that go along with Charles Bonnet Syndrome. Other topics include sensory deprivation, hearing things, Parkinsonism hallucinations, drug induced hallucinations and more.

I was a little disappointed that Sacks didn’t go into schizophrenic hallucinations but as he remarks in the book, schizophrenia requires its own book to do justice to the levels of complexity there. I look forward to reading it.

Sacks includes a lot of personal anecdotes from various people, including patients, famous cases, other scientists, and people who have written to him. This gives a human face to the descriptions and causes of the various types of hallucinations. The anecdotes are always interesting and some of the people are quite extraordinary. Following up with the personal stories, Sacks will explain the neurology behind the tales and discuss the scientific context.

The sheer verity of types of hallucinations that exist was staggering. From purely visual, auditory, tactile and olfactory, to hallucinations that interact with and communicate with the hallucinator. The causes themselves are as varied as the types. Some are brought about by sensory deprivation – blindness can lead to visual hallucinations, others by damage to different parts of the brain. There is a lot to learn here.

There is also an abundance of footnotes with back story, science history, and references for the dedicated reader. Some of the material is good enough to be included in the text of the chapters and I hope people take the time to read it, the history of studying hallucinations is as interesting as the hallucinations themselves.

One of the key themes is highlighting the stigma attached to hallucinations. Mental illness, despite being prevalent in our society, is still very much a social taboo. The fear of be labelled “crazy” can lead people to suffer in silence and hallucinations in particular carry significant baggage. My own lack of understanding is a perfect example. I had no idea that hallucinations could be as passive as they actually are. Popular culture would led one to assume that such episodes would be devastatingly debilitating, in fact, almost everyone that Sacks mentions are able to live full lives and are not debilitated at all by their hallucinations.

The stigma comes up constantly. Sacks discusses the impact in this quote:

“When I worked in a migraine clinic as a young neurologist, I made a point of asking every patient about [migraine hallucinations] experiences. They were usually relieved that I asked, for people are afraid to mention hallucinations, fearing that they will be seen as psychotic.” (Sacks, Page 127)

And again when Sacks attended a narcolepsy support group in New York:

“Cataplexy – the sudden, complete loss of muscle tone with emotion or laughter – affected many at this meeting, and it was freely discussed. … But hallucinations were another matter: people often hesitate to admit to them, and there was little open discussion of the subject, even in a room full of narcoleptics. Nonetheless, many people later wrote to me about their hallucinations,” (Sacks, Page 220)

As I mentioned, there’s a lot to learn in this book, and indeed the material is very fascinating, I flew through it in a matter of days. In my opinion, the most intriguing chapters were where Sacks discussed his own experience with hallucinatory drugs and the effects he experienced while using them, including dramatic instances where Sacks hallucinated whole conversations with non-existent people, and wandering around New York city while under the influence.

My other favourite chapter is ‘Narcolepsy and Night Hags’ from which I quoted above. Of particular interest for me was the discussion of sleep paralysis, which I occasionally have. Usually once a month I awaken suddenly to find I can’t move and experience strange sensations like the uncomfortable feeling that I’m not alone or that something is lurking next to my paralyzed body. Occasionally I’ll hear noises or feel something touching my skin. Seconds later I’ll regain the ability to move and discover no nocturnal terror waiting for me. I’m so familiar with the sensation now that when it occurs I can usually recognize what’s happening and it’s not as terrifying. (I wrote a bit about sleeping before on Skeptic North)

While my experiences with sleep paralysis have been disturbing, I’ve never experienced its most famous feature, waking to discover something sitting on or suffocating you. This is brought about by the trouble breathing many have during an episode and it’s also the namesake of the word ‘nightmare.’

“The ‘mare’ in ‘nightmare’ originally referred to a demonic woman who suffocated sleepers by laying on their chests (she was called ‘Old Hag’ in Newfoundland). Ernest Jones, in his monograph On The Nightmare, emphasized that nightmares were radically different from ordinary dreams in their invariable sense of a fearful presence (sometimes astride the chest), difficulty breathing, and the realization that one is totally paralyzed.” (Sacks, page 227)

Sacks also provides some interesting context that hallucinations like sleep paralyses have in pre-science society. Folk lore of Old Hags, sleep demons and angelic visitations become far more understandable when looking at the powerful effects hallucinations can have on the human psyche. Sleep demons may have gone out of style these days, but we’ve replaced them with ghosts and alien abductions.

Most of the hallucinations Sacks talks about are random generations of the mind, they aren’t particularly relevant to the people who have them. As such, he rarely dives into the meaning behind them, which is logical since they are seemingly randomly generated independent of the beliefs of the person hallucinating them. Sacks is a neurologist as well, so his interest appears to be on the cause and not so much the meaning or interpretation behind hallucinations.

This randomness and independence from the person having the hallucination is what sets them apart from dreams, which are by-products of the beliefs, experiences and personality of the dreamer. So for readers interested in a more psychological approach might be disappointed with the book.

The only other weak area I found was I would have liked a more comprehensive conclusion. The book, fairly anticlimactically ends. Again, understanding that this is a “how” book and not a “why” book, I would still have liked a stronger ending to which hang one’s hat on.

Nevertheless, if you haven’t read a Sacks book before, this is a good one to start with. If you have, you probably know what to expect and if you liked his previous books, chances are you’ll like this one as well.

One Response to “Book Review: Hallucinations by Oliver Sacks”

  1. Chris says:

    I have read almost every one of his books, except I have not gotten around to his latest two. I started to read them after I had a child who had seizures and a speech disorder in order to understand the neurology. They are of varying quality, but mostly quite good reads (Seeing Voices and the one on migraines are a bit more ponderous to read, his autobiography is wonderful).

    I quite enjoyed the audiobook version of Musicophilia, so I may be doing the same with his more recent and future books.

    If you ever get to see him speak live during one of his book tours, try to go see him. He is quite an engaging speaker. When I saw him he remarked how the sign language interpreters signed “stabbed in the heart” with gusto.


  • Ethan Clow

    Ethan Clow, born and raised in the Vancouver area, is best known in the skeptical community as Ethan the Freethinking Historian, co-host of Radio Freethinker, a skeptical podcast and radio show on CiTR in Vancouver. And as the former Executive Director of the Centre for Inquiry Vancouver. Ethan graduated with a B.A. in History from UBC in the fall of 2009 and has an active role with skeptical movements in Vancouver and British Columbia. He was an executive member of the UBC Freethinkers, a campus club that promotes skepticism and critical thinking. He still maintains a close relationship with the UBC Freethinkers and helps plan events and organizes skeptical activism as best he can. Currently he works for the Centre for Inquiry as the Executive Director of CFI Vancouver.