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Greek scientists > Sleep for better health December 11, 2006

Posted by grhomeboy in Health & Fitness.

A low metabolism and weight gain for those who don’t get enough

Two Greek scientists have found that a systematic lack of sleep is related to obesity and harms health by stressing the body. But these effects can be eased by taking a two-hour nap in the afternoon, a common habit in Athens three decades ago, before lifestyles sped up to today’s frenzied pace.

Professors Alexandros Vgontzas (of the Sleep and Research Treatment Center at Penn State University’s College of Medicine) and George Chrousos (of the US National Institute of Child Health and Human Development), in an article in the American Journal of Physiology, studied for five years the effects of sleeplessness on the metabolism and discovered it can be hazardous to one’s health.

«We should get as much sleep as our bodies need,» said Chrousos, who is also professor of pediatrics at Athens University. «When someone is sleepy, their minds do not work properly, and they are not alert. They are more likely to cause a road accident and cannot work efficiently. If we don’t get enough sleep over a long period of time, our metabolism changes and we age faster,» he explained. «Sleep has restorative and corrective properties. It corrects minor damage before it can accumulate and cause serious problems.»

Not all people have the same needs, so normal sleeping patterns can range from six to eight hours, depending on the individual.

«First of all we deprived healthy people of sleep for one night and the next day subjected them to laboratory and other tests,» said Chrousos, describing the experiments. «We saw that levels of interleukin-6, which is a cytokine [a proteinaceous signaling compound used extensively for inter-cell communication] produced by the immune system, had increased. This hormone creates a resistance to insulin and a tendency to obesity. Every time the levels of insulin in the blood rise, this causes very slight damage, but over a long period of time causes visceral obesity and this can undermine our health as a major cause of cardiovascular disease.»

The next experiment was also on healthy people who were deprived of two hours of sleep a day for a week.

«We wanted to see if this slight sleep deprivation, which is very common these days, can affect metabolism,» Chrousos said. «In fact, a week later we saw that the participants were sleepy, tired, had increased levels of cytokines and metabolic anomalies. We tested their levels of mental clarity, alertness, and above all their effectiveness in carrying out tasks and found that these levels had all dropped. That is, just a small reduction in the number of hours’ sleep over a week had a number of negative effects.»

A two-hour afternoon nap can rejuvenate you after a late night > A nap every afternoon helps us get through the rest of the day much more effectively than a strong cup of coffee, the study says. A two-hour siesta, in fact, is enough to rejuvenate us after a really late night.

«Afternoon naps are really beneficial,» Chrousos said. Laboratory tests show that hormone levels return to normal after a two-hour nap, and participants said in response to a questionnaire that they no longer felt sleepy or tired.

Further tests showed that people made fewer mistakes and worked more efficiently. The levels of cortisol in the blood (a hormone that is considered harmful if it remains at high levels over long periods of time) fell after a late night, but after a short afternoon nap, they rise just enough to make us feel better. Getting enough sleep contributes to a proper balance of hormones and is necessary for good health. This particularly applies to young schoolchildren and students who often do not get as much sleep as much as they should.

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