*quoted from metabolic.com
Stuart Jeffries wrote in The Guardian of 29 Jan 2011:
“You’ve got it all wrong if you’re reading this after a delicious post-lunch snooze. Humans are monophasic sleepers not polyphasic ones, siesta lovers and cat nappers notwithstanding. Some time between 70,000-40,000 BC, Neanderthal man stopped the non-human primate pattern of polyphasic sleep (which involves multiple rest-activity cycles in a 24-hour period) and adopted monophasic (sleep at night, awake by day) patterns instead. Ever since then, sleep has bedevilled us and kept many scientists awake at night …
• Between 5,000 and 1,000 BC, early civilisations such as Mesopotamia, India, Egypt and China used remedies including chanting, divination, blood-letting and medicinal plants to regulate sleep patterns and dreams.
• Human monophasia was given intellectual gloss in 1180 when philosopher-physician Moses Maimonides argued that a single nocturnal sleep lasting one third of a day’s 24 hours was sufficient for humans. Maybe he was right: Margaret Thatcher subsisted on four hours a night – and look what she did to the country while the rest of us were asleep.
Is sleep governed ultimately by circadian rhythms (“circa” means round, “dia” day)? It’s a question that has intrigued sleep scientists since 1729 when Jean Jacques d’Ortuous de Marian put some plants in dark rooms for several days. Even without sunlight, these specimens (which normally open their leaves by day and close them at night) continued their daily ritual. Marian concluded circadian rhythms persist without environmental cues.
• Do we, similarly, have biological clocks? In 1938 two sleep researchers, Nathaniel Kleitman and Bruce Richardson, retreated for 32 days into Mammoth Cave in Kentucky to find out. Deprived of environmental cues, they tried to switch to a 28-hour sleep cycle. After 32 days, their beards were superb but their results inconclusive.
• Their work inspired another sleep researcher, Jurgen Aschoff, who, 20 years later and with the aid of Nato, put more humans in a sun-free environment and measured their urine output and body temperatures. Aschoff found that, like plants, we have endogenous (ie having an internal cause) circadian cycles. Aschoff had found that our circadian sleep cycles were not dependent on environmental cues such as sunlight or darkness.
• Are there also different stages to sleep? In 1924, German psychiatrist Hans Berger, the first to record the human brain’s EEG (electro-encephalogram), noticed different wave patterns between sleeping and awake brains.
• In 1952, our cave-dwelling chum Kleitman discovered rapid eye movement (REM) – a normal phase of sleep that occurs around four or five times a night, during which vivid dreams occur and lighter sleep is experienced.
• In 1968, two researchers, Allan Rechtschaffen and Anthony Kales, published the first EEG manual of so-called R&K criteria to score sleep stages. They are still used today and consist of four non-REM stages of sleep plus REM sleep. The non-REM stages are divided by monitoring brain waves. Our deepest sleep (AKA slow-wave sleep) consists of stages 3 and 4 of R&K’s non-REM stages. If you’re aroused from slow-wave sleep you are typically cognitively challenged – don’t expect to be able to find your socks, let alone make a decent espresso.
• Interesting, but not as interesting as narcoleptic dobermans. In 1973, after narcolepsy was reported in two doberman pinschers, a colony of the dogs was established at Stanford University. Research on the dobermans led to the discovery of a hypocretin/ orexin mutation in them which broadened our understanding of the causes of narcolepsy.
It is now known that complex HLA-DR and DQ interactions confer risk of narcolepsy with cataplexy syndrome. HLA-DRs and DQs, incidentally, are antigens that work in the immune system; cataplexy syndrome is a sudden loss in muscle tone, such as facial muscles sagging or one’s jaw or head dropping sharply. Not even really clever dobermans knew that before. Or, frankly, since.
• In the 1970s, US psychologist Richard Bootzin demonstrated that insomnia may be a maladaptive conditioned response to the bedroom environment (like winceyette nighties, only more so), prompting huge interest in sleep psychology, and – you’d think – sales of blackout curtains.
• But insomniacs need more than nocturnal self-regulation. In 2005, the US National Institutes of Health argued that cognitive behavioural therapy is the treatment of choice for insomnia. How we’ve changed: hardly any CBT involves chanting, divination or blood-letting.”