Head Trip

A quick post to recommend the 2007 book Head Trip, by Jeff Warren.

Head Trip is about "24 hours in the life of your brain": sleeping, waking, and everything in-between, from lucid dreaming to daydreams and hypnosis.

Warren gives a nice overview of current research and theory along with the story of his personal quest to experience the full spectrum of conciousness.

The book's most interesting chapter is called "The Watch". It's about that hour or two of wakefulness which occurs in the middle of the night, between the first sleep and the second sleep. You know the one...right? Neither did I, but apparently, this makes us a bit weird, historically speaking.

Warren says that until the era of artificial lighting and alarm clocks, sleep was segmented. It was common for people to sleep twice each night, with a bout of awakeness in the middle. This nocturnal alertness wasn't quite like daytime waking, though: it was more relaxed, less focussed, carefree. Our modern sleep pattern, then, is kind of compressed, with the two sleeps pushed together until they merge into one.

There are two lines of evidence for this. Writings from the pre-modern era routinely make reference to "first sleep" and "second sleep", and in many languages, although not modern English, there were special words for these periods and the wakefulness between. This is according to historian A. Roger Ekirch in his history of night-time, At Day's Close (review, Wiki), a book I really want to read now.

On the other hand, there's the findings of sleep psychiatrist Thomas Wehr, in particular his classic 1992 study called In short photoperiods, human sleep is biphasic. Wehr took healthy American volunteers and put them in an artificial environment with a controlled light cycle, such that there were only 10 hours of brightness per day. (That's 6 hours less than we get on average, even in winter, due to artificial light.) Within a few weeks "their sleep episodes expanded and usually divided into two symmetrical bouts, several hours in duration, with a 1-3 h waking interval between them."

This is pretty freaky. Sleeping all night seems natural, normal and healthy: if we wake up before we need to get up, we're dismayed and we call it insomnia. Maybe this is a modern invention like electric lighting. There's something amazing and also a bit disturbing about this idea. As Warren says, it's like finding out that your house "is really the exposed bell-tower of a vast underground cathedral".