Professor Philippa Gander, director of the Sleep/Wake Research Centre, based at Massey University in Wellington, says there is growing interest in the idea that what we conceive of as normal and healthy – eight hours of solid sleep a night – is an artefact of artificial lighting.
Insomniacs might be reassured by a series of studies in the US that found that given 14 hours of absolute darkness, people tend to sleep in two distinct chunks, with a period of wakefulness in the middle. There is plenty of evidence that past societies, attuned to the hours of daylight, slept this way. An historian told the Baltimore sleep conference that the idea of two sleeps crops up often in old literature. “All the way back to the Greeks they talk about first sleep and second sleep,” Gander says. About the time of the Industrial Revolution, and the advent of cheap artificial light, “there started to be a whole popular movement against the evils of the second sleep. It was a time for lasciviousness and laziness and all that sort of thing, and ‘real people got out of bed and got on with waking things’.”
Waking in the middle of the night is now a common complaint, often diagnosed as insomnia. About 20% of people prescribed sleeping pills will pop them at that point. “The implication is that quite a large proportion of people may be taking sleeping pills for no good reason other than to try to cover up their natural pattern,” Gander says.
“One of the questions that was being discussed in that symposium is: are we making a big mistake here? Is that just people who have a normal sleep pattern and they shouldn’t be worried about it?”
Eight hours’ sleep might be the best we can aim for in modern society, but it may not be the natural human sleep pattern.
“It’s certainly unusual – other animals don’t do it. Other primates don’t do it.”
In an ideal world, says Gander, perhaps what those people should do is try to sleep in for longer each morning and accept that wakeful time at night is normal.
Fine for a caveman, perhaps, but try explaining that to the boss.
For ways to get a good night’s rest, read this week’s Listener cover story: In search of sleepSubscriber contentIcon definitionSubscriber content