Death by Office Chair, Death by Shift Work

http://journals.lww.com/acsm-msse/Abstract/2009/05000/Sitting_Time_and_Mortality_from_All_Causes,.5.aspx I'm surprised they found such a strong correlation here. It looks to be a quality study. Even the physically active have a 40% kick-up in mortality between the never-sitters and the almost always sitters. For the obese it's much worse: the mortality rate jumps fourfold. Most of the increase in risk for all sub-categories occurs between those sitting half the day and those sitting all day. So, if you keep to your feet half the day, you avoid almost all of the risk from sitting. This may be part of the reason: "Marc Hamilton, Ph.D., one of Katzmarkzyk’s colleagues, suspects it has to do with an enzyme called lipoprotein lipase (LPL), which breaks down fat in the bloodstream and turns it into energy. Hamilton found that standing rats have ten times more of the stuff coursing through their bodies than laying rats. It doesn’t matter how fit the rats are; when they leave their feet, their LPL levels plummet. Hamilton believes the same happens in humans." It may be that inadequate LPL causes blood fats to accumulate in the bloodstream, which may cause an inflammatory or clotting effect. There was also another study on this issue, comparing street car or trolley drivers who stood on the job and bus drivers who sat. All I remember is that it appeared to be a well-controlled study, the standers lived 5 years longer than the sitters, and most of the sitters' excess mortality was from cardiovascular disease. One more touchstone worthy of mention is a study, at least reasonably well-controlled, that indicated a 5 year survival advantage for those who consistently slept well and at night compared to those who slept poorly most of the time.