British civil servants (government office workers) provided the database for an interesting survey. Over 10,000 civil servants aged 35 to 55 at baseline had further assessments after 2 and 7 years. Blood pressure was measured at each assessment, and sleep duration at the 7-year exam. The findings of this study - the Whitehall II Study - were reported in the journal Hypertension.

Of the 5,766 subjects examined in the 7-year assessment, 5 hours' or less sleep a night was linked with an increased risk of high blood pressure (over 140/90 mm Hg or on antihypertensive medication); this association was found in women only, in comparison with women sleeping 7 or more hours nightly. The short-sleeping women were twice as likely to have hypertension as their long-sleeping sisters. Those sleeping around 6 hours a night were bout 1½ times as likely.

Last month I wrote about a study showing increased mortality in people sleeping much more, or less, than 7 hours a night. Perhaps the cardiovascular effect of sleep lack may contribute to the effect on mortality. Or the recognized effect on weight? (Weight was not factored into the analysis of the Whitehall II Study.) Anyhow, make sure you get just the right amount of sleep!