Too much, too little sleep can be deadly

LONDON, Dec. 3 (UPI) -- Sleeping too much, or too little can increase the risk of mortality, British researchers found.

A study, published in the journal Sleep, linked a decrease in sleep duration in people who slept between six to eight hours per night to a 110 percent excess risk of cardiovascular mortality. An increase in sleep duration among people who already sleep seven or eight hours was linked to a 110 percent increased risk of mortality.

"In terms of prevention, our findings indicate that consistently sleeping seven or eight hours per night is optimal for health," the study's author, Dr. Jane Ferrie, of University College London Medical School, said in a statement.

The study involved 10,308 participants between 35 and 55. Baseline screening was conducted between 1985 and 1988 and included a clinical examination and a self-administered questionnaire. Information was again collected through an exam and questionnaire from l992 to l993, by which time there were 8,642 participants.