The Industrial Revolution was a pivotal moment in the history of labor, marking the turning point when humanity began to shift from a farming and handicrafts based economy, to one of mass manufacturing and production.
And while the changes in our society were obviously monumental (to put it mildly), heralding the way for stuff like conveyor belts and factory life, it's also worth reflecting on how those sudden changes profoundly affected the way humans sleep.
Prior to the 18th century much of humanity used to have two distinct resting periods where farmers and workers caught up on some sleep, versus today's solid eight hours of sleep a night in the United States.
The two sleeps of the past are called 'segmented sleeping' in today's terms, and were often referred to in Europe as "first sleep" and "second sleep" according to a seminal research paper on the topic published by history scholar A. Roger Ekrich. His 16 years of research uncovered references to the two "sleeps" as far back as in Homer's ancient epic Odyssey, composed around 800 BC.
Through the ensuing millennia, Ekrich's paper relates dozens of references in printed works about the two sleeps, along with anecdotes about how people used to spend their time: sex, mischief, contemplation, and farm labor.
But two major things changed in conjunction during the Industrial Revolution, which would alter everything: social attitudes toward the night and the widespread availability of light—namely in the forms of gas lamps and the electric light bulb.
Before the 18th century, night was a pretty scary time for most people, even the rich, who could only afford to buy light-producing objects such as candles. But as light technology became more prevalent, and evening activities more common—up until the 17th century, most people out at night were either drunk or looking for prostitutes, according to the paper—we began to change our sleeping patterns to suit our new access to later hours.
It didn't happen overnight, either. Just as the Industrial Revolution actually took several centuries to completely unfold, it was really only until the 1920s when references to first and second sleep dried up. And nowadays, the conventional wisdom is that eight hours of sleep is what's healthy, with segmented sleep rarely mentioned in the US except in reference to the Spanish siesta.
The thing is, our bodies aren't built for sleeping in eight hour blocks. For example, Dr. Thomas A. Wehr, a psychiatrist, experimented by removing artificial light from the equation of test subjects—that meant no smart phones, laptops, or even light bulbs for 14 hours a day. At first there wasn't any change, but after several weeks of experimentation the Wehr's subjects ended up reverting to the first and second sleep pattern that's been around at least since Homer.
sleeping eight hours a night suits the 'nine to five' workplace.
There's more science behind segmented sleeping as well. According to a New York Times article, a NASA-financed study found that the cognitive benefits of sleeping can be achieved after as little as 24 minutes of napping.
It's also worth remembering that sleeping eight hours a night suits the "nine to five" workplace. The point is, for the most part, aside from lunch and water cooler chats (which aren't usually long enough for a nap, anyway), work time is relatively uninterrupted.
But as Bloomberg Businessweek reports, nap rooms and indeed, mid-day naps, are beginning to be adopted by several American companies looking to recoup the billions wasted each year on unproductive workers who are sleepy on the job. Yet for the vast majority of us toiling nine to five at places without nap times, labor conditions make it difficult for us to sleep in segments.
So, next time you wake up in the middle of the night with insomnia, it's worth considering that it may well be because for most of humanity's recorded history, that's the way our bodies have worked. And if you're awake after your first sleep, it may be worth pondering the extent technology will alter our body's fundamental sleeping rhythms in the future, and how it already has.