How much Sleep do we Need?
Recent research tries to find out what influences our Sleep Patterns and if we really require Seven Hours of Shut-Eye.
For years, public health authorities have warned that smartphones, television screens and the hectic pace of modern life are disrupting natural sleep patterns, fuelling an epidemic of sleep deprivation. But now a new study is challenging that notion. It found that Americans on average sleep as people in three different hunter-gatherer societies, where there is no electricity and the lifestyles have remained largely the same for thousands of years. If anything, the communities included in the new study – the Hazda and San tribes in Africa and the Tsimane people in South America tend to sleep even less than many Americans.
The findings are striking because health authorities have long suggested that getting a minimum of seven hours on a consistent basis is a necessity for good health. Many studies suggest that lack of sleep, independent of other factors like physical activity is associated with obesity and chronic disease.
Yet the hunter-gatherers included in the new study, which was published in the journal Current Biology, were relatively fit and healthy despite regularly sleeping amounts that are near the low end of those in industrialized societies.
The prevailing notion in sleep medicine is that human evolved to go to bed when the sun goes down and that by and large, we stay up much later than we should because we are flooded with artificial light, said Dr. Jerome Siegel, the lead author of the new study and a professor of Psychiatry at the Semel Institute of Neuroscience and Human Behaviour at UCLA.
But Siegel and his colleagues found no evidence of this. The groups they studied, which slept outside or in crude huts, did not go to sleep when the sun went down. Usually they stayed awake three to four hours past sunset, with no light exposure other than the faint glow of a small fire that would keep animals away and provide a bit warmth in the winter. Most days, they would wake up about an hour before sunrise. In a typical night, they slept just six and half hours.
Members of the various tribes were fitted with small wristwatch like devices that tracked their sleep patterns and their exposure to light across the seasons.
The researchers found that in addition to sleeping roughly similar amounts each night, the three groups rarely took naps during the day and did not sleep in two separate intervals at night. Siegel said it was remarkable how closely their sleep patterns overlapped despite the distances between them.
Jim Horne, the director of the Sleep Research Centre at Loughborough University in England, called the new study “Excellent and very timely”, and he said it suggests that sleep quality is much more important than quantity.
Siegel said that ambient temperature may be a major factor. The groups in the study did not go to sleep at sunset and they did not wakeup at sunrise, but they almost always fell asleep at temperatures began to fall at night and they would wake up right as the temperatures were rising again.
This suggests that humans may have evolved to sleep during the coldest hours of the day, perhaps as a way to conserve energy, Siegel said.
“Today, we sleep in environments with fixed temperatures, but none of our ancestors did”, Siegel said. “We evolved to sleep in a natural environment where the temperature falls at night. Whether we can treat insomnia by putting people in an environment where the temperature is modulated in this way is something to be studied in the future”.
-Source: THE HINDU (News Paper)