When I was a child, I had a fever
My hands felt just like two balloons
Now I’ve got that feeling once again
I can’t explain, you would not understand
This is not how I am.
–Pink Floyd, “Comfortably Numb”

In the era before modern antibiotics and fever-reducers, I probably wouldn’t have survived childhood. I experienced severe chronic tonsillitis when I was 3 or 4 years old, resulting eventually in the doctor’s decision to remove my tonsils entirely. During the bouts of illness, I had really high fevers, with accompanying delirium. My father told me later that I hallucinated turning him into a “monster with glowing eyes”, which I don’t remember now. However, I do remember seeing scuttling crabs on the floor, and a variety of other bizarre frightening fever-induced hallucinations. The most extreme fevers vanished after the tonsillectomy, thankfully. (Another side effect: my hair color changed from almost pure white to yellow-blond. Today what’s left of it is very dark blond.)

Later in my childhood, I had a recurring fever vision in which the room became simultaneously huge and tiny. Another recurring hallucination involved turning the bumps in the plaster ceiling into holes, which sounds innocent but which was terrifying at the time. In my delirium, I somehow associated those holes with a fatal threat to me, and to this day when I see something that inspires the optical illusion switching back and forth between a bump and a hole (see the image to the left), I feel a ghost of that sensation. These hallucinations are impossible to describe adequately, yet I can recall them very well even at a space of 30 years.

I’ve had a few other minor hallucinatory experiences, but I won’t recount them here. According to the book Hallucinations by neurologist Oliver Sacks, hallucinations of some sort are fairly common, to the point where nearly everyone experiences them at some point in their lives. Sacks covers the huge variety of phenomena that generally fall under the category of hallucinations: near-death experiences, epileptic auras, feverish delirium, phantom limbs, drug-induced synaesthesia, and so forth. Some of these conditions are pretty well understood in terms of neurology; others less so (though Sacks appears to trust they eventually all will be described as such – no mystic, he). The book is slightly disjointed due in part to the wide scope – a problem his previous work Musicophilia also suffered – so it might be better structurally to think of it as semi-independent essays rather than describing an undivided narrative arc.

As usual in Sacks’ books, the story is enlivened by case histories, including many from his own life. His stories about taking hallucinogenic and opioid drugs show both a fascinating look into specific experiences, but also (inadvertently) the dangers inherent in believing we’re fully in charge of our own brains. That’s a lesson reinforced throughout the book: under a number of conditions, both internal and external, we can be betrayed by our own minds. Most of us see, feel, hear, smell, and touch things that aren’t there at some point in our lives, and books like this can help reduce the stigma. By understanding hallucinations as natural phenomena, we can use them to understand ourselves better.

The Pink Floyd song quoted at the top of the post describes a delirious hallucination; Sacks notes that not only can hands feel like balloons in hallucinations, sometimes they can appear like balloons too, or even stranger apparitions. My childhood hallucinations were fairly minor, all things considered. As real as they were at the time, they were easily dismissed as products of my fevers, but other hallucinations are a lot more disturbing or uplifting to the person experiencing them. However, one thing of interest is how persistent the memories are. Unlike the recollection of real events, which all of our experiences shape and distort, the memory of hallucinations are vivid, probably because they aren’t real.

Today is the birthday of Edgar Allan Poe, born this day in 1809. Poe famously used hallucinatory images in his fiction and poetry, but (as Sacks points out) also experienced vivid fantastic hallucinations when falling asleep—a common form known as hypnogogic hallucinations—which he would write down as literary fodder. I’ve had hypnogogic hallucinations on occasion, and chances are that you have too. Not all of us have the skill to turn the fantastical involuntary sparkings of our brains into art, but it’s good to know that they are part of our makeup, not the curse of a devil.