Sleep Duration & Risk of Death

The AASM reports that most adults need about seven to eight hours of nightly sleep to feel alert and well rested during the day. But is it dangerous if you regularly get less sleep or more sleep? Does “short sleep” or “long sleep” increase your risk of death?

A new study took a look at the evidence. The systematic review analyzed data from other studies. In each study sleep duration was measured by self-report.

Sixteen studies measured short sleep and mortality. The combined results show that having a short sleep duration was associated with a 10 percent increase in the risk of death.

Why? Other research offers possible explanations. Studies have linked short sleep to an increased risk of diabetes, obesity and hypertension.

What about long sleep duration? Seventeen studies reported data on long sleep duration and mortality. The risk of death for long sleepers was increased by 23 percent; their risk of cardiovascular-related death was increased by 38 percent.

A 2008 study in the journal Sleep suggested a possible explanation for this relationship. The study involved 9,789 U.S. adults between 32 and 86 years of age.

There was no link between sleep duration and mortality in middle-aged adults between the ages of 32 and 59. But in elderly adults between 60 and 86 years of age, both short sleep and long sleep were associated with an increased risk of death.

The mortality risk was increased by 27 percent in elderly adults who reported that they usually sleep five hours or less; the risk was increased by 36 percent in older adults who reported sleeping nine hours or more.

“The relationship between sleep duration and mortality is largely influenced by deaths in elderly subjects,” the authors concluded. “Long sleep duration is unlikely to contribute toward mortality.”