dormez bien

British researchers suggest that a lack of sleep or poor sleep can have profound effects on the workings of the human body.

Heart disease, diabetes, obesity and poor brain function have all been linked to substandard sleep.
What missing hours in bed actually does to alter health, however, is unknown.

How this dovetails with the fact that there are people who sleep very little -- and some not at all -- without ill effect, I'm not sure.