meta-analysis of 12 studies published in this month's issue of the American Journal of Epidemiology , the authors found that working long hours (defined as >10hrs/d) was associated with a 40% increase risk of heart disease in 4 prospective studies and 143% increase risk in 7 case-control studies. With the addition of a single cross-sectional study, the authors assessed risk in 22,518 participants in widely different types of research studies. But the important point is that the studies all have similar conclusions.
But while these are but observational or epidemiologic studies capable only of helping to develop hypotheses but not at generating proof of cause & effect, it does give one pause to think about why this relationship exists and what can be done to prevent the proof from getting stronger.
On the other hand, if long work hours leads to insomnia & inadequate sleep, it might reflect in performance issues as noted in a survey of 4,991 employees as published in this month's Archives of General Psychiatry . In fact, insomnia-related errors rang up an average of $32,062 compared to $21,914 for non-insomnia related accidents w/projected costs of $31.1B due to insomnia in the States. Hmmm . . . on second thought, perhaps I shouldn't mention this study? And when did I miss my bedtime again?