From The Daniel Island News

Sleep: is it normal to wake up in the middle of the night?
By Steve Ferber
May 8, 2013 - 9:00:56 AM

Forget everything you know about sleep.  Doing so just might help you get a full night’s rest.
Let’s start with the notion that human beings need eight hours of continuous sleep. We probably don’t. But thinking that we do can easily trigger sleep anxiety, which on its own can cause a person nightmares.   
Blame Thomas Edison, if you must (or, perhaps, the city of Paris which in 1667 became the first city in the world to light its streets).  Prior to the advent of the light bulb, and the Industrial Revolution, human beings were known to sleep in two segments, known as “first sleep” and “second sleep.”  That is, people would go to bed after sunset, wake up roughly four hours later (for an hour or two, or three), then return to bed for their “second sleep,” of another lengthy duration.  
Sleep psychologist Gregg Jacobs, as quoted in a BBC World Service report, maintains that “Waking up during the night is part of normal human physiology.”  And historian and author Roger Ekirch would quite agree.  The Virginia Tech professor spent over 15 years researching historical sleep patterns and revealed his findings on segmented sleep in a landmark paper, published in 2001 (four years later he authored a book titled “At Day’s Close: Night in Times Past”).  
Ekirch, quoted on the website, said that sometime in the 18th and 19th century “language changed and references to segmented sleep fell away . . .. Now people call it insomnia.” By the 1920s, according to the BBC article, “the idea of a first and second sleep had receded entirely from our social consciousness.” The BBC article continued: “[Ekirch] attributes the initial shift to improvements in street lighting, domestic lighting and a surge in coffee houses – which were sometimes open all night. As the night became a place for legitimate activity and as that activity increased, the length of time people could dedicate to rest dwindled.”
 The notion that segmented sleep is our natural state is backed by research undertaken 20 years ago by Thomas Wehr, a psychiatrist at the National Institute of Health. Explains an article at
“Wehr did experiments where he kept humans away from artificial light of any kind. After a couple of weeks, they started to fall asleep early – right after the sun went down – and then wake up after midnight. They’d lie awake for an hour or so and then fall back asleep . . .. Deprived of light, the subjects resorted to historical norms, dividing up their sleep into two distinct periods . . .. Wehr also found that this period between the first sleep and the second sleep was the most relaxing time of the day, almost akin to some yogi-like meditation. He confirmed this observation biochemically as he found that subjects were pumping out large amounts of prolactin, the post-orgasm hormone, during this mid-sleep period.”
How much sleep do we need?
Is 8 hours the right number?
Not only is the verdict out on this, but one study in particular – collating results from a million subjects – found that people who averaged between 6-7 hours a night ended up living longer than those who grabbed eight hours (or more).  Given that the U.S., by and large, is a sleep-deprived nation, no one is advocating that people cut back on their sleep, but the notion that you’re getting less than eight a night might again be causing unnecessary sleep anxiety.  
And how about naps?
 How effective are they?  
Wrote David Randall, in an article for the New York Times: “The idea that we should sleep in eight-hour chunks is relatively recent. The world’s population sleeps in various and surprising ways. Millions of Chinese workers continue to put their heads on their desks for a nap of an hour or so after lunch, for example, and daytime napping is common from India to Spain.”
Robert Stickgold, a professor of psychiatry at Harvard Medical School, proposes that sleep — including short naps that include deep sleep — offers our brains the chance to decide what new information to keep and what to toss. Said Stickgold, in an NRP-led roundtable discussion on sleep:
“ . . . [W]e’ve done some studies looking at naps in terms of the memory processing and have been rather stunned, really, by the fact that in almost every experiment that we’ve tried, an hour-and-a-half nap seems to do as much good for memory processing as an entire night of sleep, and we continue to ponder that and sort of conclude that OK, we just don’t get it yet. But in studies where six hours of sleep at night seems not enough to lead to consolidation of memory of a particular task, an-hour-and-a-half nap will. So there’s something, at least from the memory perspective, rather magical and unusually efficient about napping as opposed to nocturnal sleep.”
David Dinges, a professor at the University of Pennsylvania School of Medicine undertook a series of studies on the effectiveness of naps, giving volunteers a series of tests on memory, alertness, response time, and other cognitive skills (they also measured biological systems, such as core body temperature and hormone levels). No surprise, Dinges found that longer naps were better, but some cognitive functions benefited more from napping than others.  
Said Dinges, as quoted in a NASA article: “To our amazement, working memory performance benefited from the naps, [but] vigilance and basic alertness did not benefit very much.”
 Working memory,” he explains, “involves focusing attention on one task while holding other tasks in memory ... and is a fundamental ability critical to performing complex work [like piloting a spaceship]. A poor working memory could result in errors.”
Concluded Randall, author of Dreamland: Adventures in the Strange Science of Sleep: “Strategic napping . . . could benefit us all. No one argues that sleep is not essential. But freeing ourselves from needlessly rigid and quite possibly outdated ideas about what constitutes a good night’s sleep might help put many of us to rest, in a healthy and productive, if not eight-hour long, block.”

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