What insomniac fruit flies tell us about the importance of a good sleep
A variety of studies, some quite bizarre, have shed light on the importance of sleep and what happens if we don't get enough
If you're reading this after a long night's sleep, maybe catching up on some shut-eye after being awake too long on weekdays, ponder this: Nasa is funding research into extremely long sleep. Sleep of a bizarre kind, that is.
The study is being conducted by US firm SpaceWorks Enterprises, and aims to see if it is viable to put humans into a torpid state for long space flights, like a trip to Mars that could last 180 days. Subjects are chilled from the inside out using cooling pads and a nasally inhaled coolant, then hooked into an intravenous drip to supply nutrients. The metabolic rate falls by up to 70 per cent, and to date subjects have "slept" for up to seven days.
For earthbound folk, extended sleep does not deliver benefits, but can even be harmful, with the latest research suggesting the optimum nightly sleep for adults should be around seven hours. You may be unsurprised to learn that Hong Kong is among places where too many people are sleep underachievers, with a 2012 study led by Dr Wong Wing-sze, an associate professor at the department of psychological studies at the Hong Kong Institute of Education, reporting that some 2.2 million adults suffer from insomnia, and the average amount of sleep was just 6.46 hours.
While Dr Wong's study was conducted via phone interviews, sleep research has involved wide-ranging, sometimes bizarre methodology.
Though we spend almost a third of our lives asleep, sleep science did not really begin till 1953, the same year the structure of DNA was discovered. Dr Nathaniel Kleitman and one of his students, Dr Eugene Aserinsky, became the first scientists to report rapid eye movement (REM) during sleep. Another of Kleitman's students, Dr. William Dement, later made the association between REM and dreaming - though it has since turned out the two do not always occur together.
We are certain of the need for sleep partly thanks to experiments conducted in the 1980s by University of Chicago researcher Allan Rechtschaffen. He deprived rats of sleep for up to 32 days, by which time they all dropped dead - though it could be the cause was not actually sleeplessness, but hypothermia, wrecked immune systems, brain damage or extreme stress.
Humans, too, have been sleep deprived in experiments, though not till they dropped dead. Also at the University of Chicago, Eve van Cauter found that sleep-deprived students had weaker immune systems, increased heart rates and blood pressure, and insulin resistance, a pre-diabetic condition. With levels of appetite-suppressing leptin also down, she suggested: "It could be that a good chunk of our epidemic of obesity is actually an epidemic of sleep deprivation."
Getting too little sleep also impacts people mentally. Response times slow, making sleep driving while sleep deprived roughly as dangerous as drunk driving.
Ethical behaviour deteriorates, too. In one experiment, people kept awake all night - and deprived of caffeine - were markedly more willing than caffeine-boosted subjects to go along with a lie in order to earn extra money.
Insomnia research has even centred on fruit flies, which it turns out usually sleep for 12 hours a night. Insomniac fruit flies, it was found, regularly stumbled, had poorer appetite, were slow learners, and gained more fat than their regular counterparts.
The researchers hope to make discoveries that will benefit humans who sleep badly. These discoveries could also boost sex lives, as another study published this year found that fruit flies deprived of sleep when young spent less time courting and mating as adults.
Researchers at the University of Rochester Medical Centre in the US used hi-tech imaging to look deep into the brains of mice while they were asleep and awake. They found that brain cells contract during sleep, expanding the area between them by up to 60 per cent. Fluid then flowed between them, flushing out waste products including a protein that's a culprit in Alzheimer's disease. "It's like a dishwasher," team leader Maiken Nedergaard said.
After comparing how men and women responded to insufficient rest, Michael Breus of Duke University in the United States announced to reporters: "We found that women had more depression, women had more anger, and women had more hostility early in the morning."
Now before any frazzled female readers seek to berate me for relaying this message, it's worth pointing out that experts believe this is probably because women use their brains more than men do. "Women tend to multi-task - they do lots at once and are flexible," Jim Horne, director of the Sleep Research Centre at Loughborough University in the UK told The Australian.
And who else sleeps a lot, especially in the mornings? Teenagers, of course! Here, too, there is supportive evidence, with neuroscientists reporting that teenagers' circadian rhythms are two hours behind those of adults. These findings are so persuasive that the UK is beginning a large-scale study, involving 106 schools and almost 32,000 teenagers, with lessons starting at 10am rather than 9am.
If you did ponder on ideas for extended sleep helping humans to travel to planets, and perhaps reach for the stars, consider too that mammals' sleeping abilities may have helped ensure we are here in the first place. Barry Lovegrove, an evolutionary physiologist at the University of KwaZulu-Natal, South Africa, is among scientists who believe early mammals could have hibernated through the worst effects of the asteroid impact that killed off the dinosaurs. He figured a similar creature might survive on Madagascar, and two of his students indeed discovered a species that fit the bill: the common tenrec.
This small, shrew-like mammal looks unremarkable, but in one way puts even the most somnolent teen to shame: it can hibernate for nine months without waking.
Martin Williams is a Hong Kong-based writer specialising in conservation and the environment. He holds a PhD in physical chemistry from Cambridge University
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