Cara Parks explores how changes to our environment affect our sleep patterns:
The term jet lag was coined in about 1966; before that, a slow boat across the Atlantic or a horse ride across Asia allowed humans to adjust gradually to their new surroundings (internal clocks can adjust by approximately one hour per day). External or environmental cues to our internal clocks are called zeitgebers, German for time-givers. These factors include temperature and, most importantly, light: the most important sign for early humans on when to hunt and when to lie low came from the sun. … Our clocks reside within us; external cues sync them to the exterior world, keeping us from shifting further from the solar cycle every day. We experience jet lag because of this internal time ticking away as the sun rises and sets. ‘Whatever the exact period is for the body clock,’ an article in 2007 on jet lag in the medical journal The Lancet stated, ‘its timing needs to be adjusted to the solar day.’ That is why jet lag is known medically as desynchronosis. The traveller has become temporally untethered from her surroundings.
Meanwhile, in a review of Jonathan Crary’s 24/7: Late Capitalism and the Ends of Sleep, Erwin Montgomery and Christine Baumgarthuber recount an anecdote about the necessity of sleep:
Irritability, depression, emotional volatility, and, eventually, hallucinations plague the insomniac. Charles Lindbergh experienced the gritty discomfort of sleep deprivation during his first solo, nonstop transatlantic flight in 1927.
His 33 hours without sleep brought him nearer to disaster than did any mechanical malfunction or patch of rough weather. The night before his pre-dawn departure, Lindbergh was anxious. He slept fitfully, later recalling in his memoir that he grabbed two, maybe three hours rest before reporting to Roosevelt Field, his place of departure. Warm inside his flight jacket and lulled by the dull hum of his plane’s engines and an empty expanse of blue sky, Lindbergh felt an irresistible drowsiness come over him only few hours after takeoff. “My eyes feel dry and hard as stones,” he recorded in his flight log. “Keeping them open is like holding arms outstretched without support.” He complained of having little control over his body, and said his mind “clicks on and off, as though attached to an electric switch with which some outside forced is tampering.” He knew that to surrender to his drowsiness, even for an instant, would spell disaster, but his body had its own ideas: “[It] argues dully that nothing, nothing life can attain, is quite so desirable as sleep.”
The Dish 