Too Little or Too Much Sleep Makes You Gain Weight, More Likely to Drink and Smoke, and Exercise Less

SYDNEY—Too little or too much is more likely to make people fat, smoke cigarettes, drink heavily, and exercise less, according to one of the biggest sleep surveys in the world.

Australian sleep experts say the U.S. study is the strongest yet to expound the virtues of a good night's sleep.

The research showed that people who get between seven and eight hours shut-eye a night tend to be slimmer and generally live a healthier lifestyle than others.

People getting less than six hours, or even more than nine hours, tend to weigh, drink, smoke, and work more, but exercise less, than those getting the sleep gold standard.

The researchers involved in the National Center for Health Statistics study of 80,000 Americans said the relationship between sleep and the other factors was not clear but the connection was "striking."

Professor Ron Grunstein, head of sleep research at the Woolcock Institute of Medical Research in Sydney, said the findings are significant.

"This is the largest study of its kind to show the link between sleep hours and lifestyle problems," Prof Grunstein said.

"There's increasing proof that making the effort to get the right amount of sleep every night will have a positive impact not just on alertness, performance, and other things like driving, but your weight and behavior too."

He said prospective studies had already strongly suggested that lack of sleep could lead to obesity, especially in children and adolescents.

However, there was not yet any proof overweight or obese people could lose weight by sleeping more.

There was an alternative school of thought that regards obesity as an inflammatory condition which interferes with sleep, but Prof. Grunstein said the evidence for this was "unconvincing."

With regards to drinking and smoking, both behaviors are known to interfere with sleep, but it was also possible sleep deprivation was triggering these "risk-taking" behaviors.

"That fits with what we know about casinos wanting to keep people awake for long hours to gamble," he said.

Also, sleep deprived people were more tired and less likely to exercise.

Meanwhile, another small study of Australians showed a quarter had used painkillers to get to sleep, while 12 percent had used sleeping tablets.

Nine percent had used other drugs or medicine, according the research conducted by the Chiropractors Association of Australia.

One third of those questioned reported that their sleep quality had reduced in the last 12 months, with 40 percent citing home or work related stress as the reason.