Head Trip, By Jeff Warren

Most of us assume that we're either asleep or awake, that our consciousness is a black or white issue and there are few, if any, shades of grey. Jeff Warren suggests that our minds are always placed somewhere on an exotic spectrum of consciousness states, and this thoroughly entertaining book is his examination of that myriad of possibilities.

For the purposes of clarity, the Canadian author has split human consciousness into 12 differentiated states. Some of these are entirely familiar, such as the daydream or REM dreaming while asleep. Others are on the fringes of everyday experience: parasomnias such as sleepwalking, narcolepsy and sleep paralysis, or "the zone" which top athletes are said to inhabit during performance.

What makes Head Trip so exhilarating is that, rather than merely tell us about such weird states as the hypnotic trance or the meditative pure conscious event, Warren actually dives in and tries to experience these consciousness states for himself.

The book is split into "Day" and "Night" sections – Warren is careful not to use "Awake" and "Asleep", as these terms gradually become meaningless the further you get into the book. Of the two halves, the Day section is marginally less engaging, but is still full of terrific stuff. For example, there is a state of waking consciousness known as the SMR (sensorimotor-rhythm, named for its distinctive brainwave pattern), which combines calmness and alertness, like a cat waiting to pounce. Through simple training, this state is being used to treat sufferers of attention deficit disorder, epilepsy and other conditions without the use of medication.

Elsewhere, Warren reveals that our conventional view of the rigid adult mind is way off target. Through appropriate techniques, our neuroplasticity (how malleable our minds are) can be exploited to achieve all sorts of remarkable feats, such as the proven placebo effect of being cured of an ailment simply because we think we're cured of it.

If daytime consciousness is amazing, nighttime consciousness is doubly so. The hypnagogic state is the grey area between waking restfulness and falling asleep, in which vivid, often hallucinatory visions are experienced. Normally we don't remember these, as we proceed into full sleep, but during this time the wiring in the brain is rejigged slightly, providing a kind of problem-solving, lateral thinking completely unavailable to the waking mind. This free-thinking state is thought to be responsible for inventions and discoveries ranging from the chemical structure of benzene to the idea for Frankenstein.

While that's handy creatively, other nighttime states are just plain weird. The lucid dream, for example, where you experience a suddenly intense vision unlike dreaming at all, and become fully aware that you're asleep, yet remain in the dream. Through experiments involving pre-arranged eye movement signals, subjects have been able to communicate with experimenters while still in this state. And next time you awake in the night and can't get back to sleep, don't stress – you may be reverting to an ancient human sleep pattern. Before the invention of artificial light, it was common for people to have two night-time sleeps, with a period of restful waking in between, thought to stem from a primal need to look out for predators.

Ultimately, it's Warren's engaging first-hand experience that brings all this to life. As he undergoes hypnagogic experiments, SMR training, lucid dream classes in Hawaii or meditation in the Scottish Highlands, you're right there with him. You'll never look at waking, sleeping or dreaming the same way again.