英音朗讀: How we could sleep better – in less time

We often wear our sleeplessness as a badge( yep I read it wrong) of pride – a measure of our impossibly hectic schedules. Thomas Edison, Margaret Thatcher, Martha Stewart and Donald Trump have all famously claimed to get by on just four or five hours’ sleep a night – much less than the seven-to-nine hours recommended to most adults. Many of us are following suit: according to the Centers for Disease Control and Prevention, more than one third of US adults fail to get enough sleep on a regular basis. The consequences – including impaired memory and decision making, and increased risk of infection and obesity – are well known, but easy to ignore. When our immediate demands exceed the hours in the day, sleep is still our top sacrifice. But what if we were able to simply optimise the sleep experience so that we enjoyed most of the benefits of deep sleep, in less time? This possibility may be closer than it sounds, thanks to new ‘sleep optimisation’ techniques. Various experiments across the world have shown that it is possible to boost the efficiency of the brain’s night-time activity – speeding up the descent into deep sleep and enhancing our rest once we get there. It sounds almost too good to be true. Is it? A slower beat On a regular night, the brain cycles through many different stages of sleep, each with a characteristic pattern of ‘brain waves’, in which neurons in different regions of the brain fire together, in synchrony, at a particular rhythm. (It’s a bit like a crowd chanting or beating a drum in unison). During the rapid eye movement (REM) phases that rhythm is fairly fast – during which time we are most likely to dream. But at certain points our eyes cease to move, our dreams fade and the rhythm of the brain waves drops to less than one ‘beat’ a second – at which point we enter our deepest, most unresponsive state of unconsciousness called ‘slow-wave sleep’. It is this stage that has been of particular interest to scientists investigating the possibility of sleep optimisation. Research since the 1980s has shown that slow-wave sleep is essential for the brain’s maintenance. It allows the necessary brain regions to pass our memories from short-term to long-term storage – so that we don’t forget what we have learnt. “The slow waves facilitate the transmission of information,” says Jan Born, director of the Department of Medical Psychology and Behavioural Neurobiology at the University of Tübingen, Germany. The slow waves may also trigger the flow of blood and cerebrospinal fluid through the brain, flushing out potentially harmful debris that could cause neural damage. They also lead to dips in the stress hormone cortisol and help to rejuvenate the immune system so that it is readier to fight incoming infections. Such results led scientists including Born to wonder whether we might therefore be able to enhance the benefits of sleep and improve our daytime functioning by boosting the production of those slow waves.