Rest

In 1938 Nathaniel Kleitman and his student Bruce Richardson went down into Mammoth Cave in Kentucky and stayed there for thirty-two days, from early June into July.

The cave was chosen because deep underground the temperature is stable and there is no daylight, which made it about the best isolation available before anyone built a facility for the purpose. They took beds, food, and a plan.

The plan was to find out whether a human being could adopt a twenty-eight-hour day. Six waking periods and rest, on a schedule that did not match the sun.

The younger man adapted reasonably well. Kleitman, who was in his forties, did not. His body temperature rhythm and his sleep kept trying to run on their own roughly twenty-four-hour schedule, and on the days when the imposed clock and the internal one disagreed he was, by his own account, drowsy and dragging through his waking hours.

I like this experiment enormously and not only for the result.

Kleitman is the man who essentially founded the modern scientific study of sleep, at a time when sleep was not considered a serious subject. The prevailing assumption was that sleep was an absence: the brain switched off, nothing much happened, and there was correspondingly little to study. To take it seriously enough to live in a cave for a month, in 1938, when your colleagues thought the topic was a backwater, is a particular kind of commitment.

And the result prefigures the whole Light season, arriving from a different direction two decades before the Andechs bunker. You cannot simply decide what schedule to live on. Something internal is running and it does not take instructions.

The other thing worth noting is that Kleitman ran the experiment on himself, which was standard practice then and is a large part of why this era produced results at all. There is a long tradition of sleep researchers doing this, and it is going to matter again in a few episodes, in a way nobody involved would have chosen.

Next episode: the eyes.