People who get less than 6 hours sleep per night had an increased risk of dying prematurely in a recent study. Those who slept for less than that amount of time were 12% more likely to die early, though researchers also found a link between sleeping more than 9 hours and premature death.

The study aggregated decade-long studies from around the world involving more than 1.3 million people and found "unequivocal evidence of the direct link" between lack of sleep and premature death.

Just one sleepless night can hamper the body's ability to use insulin to process sugar in the bloodstream. Insulin sensitivity is not fixed in healthy people, but depends on the duration of sleep in the preceding night.

"Society pushes us to sleep less and less," one of the study investigators said, adding that about 20% of the population in the United States and Britain sleeps less than 5 hours.

Adults typically need between 7 and 9 hours sleep a night. If you sleep little, you can develop diabetes, obesity, hypertension and high cholesterol.