Inadequate Sleep and a Decline in Immune Function.

Some scientists are exploring possible connections between inadequate sleep and a decline in immune function.

The Archives of Internal Medicine devoted its September 18 issue to the relationship between sleep and health. An editorial called for assessment of sleep habits as a standard part of all medical checkups.

That's because short sleep can hasten the arrival of the inevitable long sleep. The largest study of sleep duration and mortality was published in February 2002 in the Archives of General Psychiatry. The Cancer Prevention Study II of the American Cancer Society followed more than a million participants for six years.

The best survival was found among those who slept about seven hours a night, the worst among those who slept less than four and a half hours. Too much sleep - nine hours or more - also was associated with a higher risk of mortality.