Slashdot Mirror
Prolonged Sitting and Poor Sleep Can Work Together To Shorten Your Life (latimes.com)
schwit1 sends word that a new study published in PLOS Medicine has examined how lifestyle risk factors can affect mortality rates, both alone and in combination with each other. Having a single major risk factor increased mortality rates slightly, but the study found that those who report multiple risk factors are significantly more likely to die early. While this includes obvious behavior like smoking and alcohol consumption, the findings also suggest prolonged sitting and unhealthy sleep patterns can strongly increase mortality rates when combined with each other, or with the obvious behaviors. "Some combinations were more deadly than others, the researchers found. Those who blended insufficient exercise with prolonged sitting were 2.42 times more likely to die during the study, and those who were also guilty of sleeping for too many hours were 4.23 times more likely die by the time the study ended. 'These findings suggest there is a "synergistic effect" among risk factors,' the study authors wrote."
No, RTFA, too much sleep (more than nine hours) is seen as unhealthy too.
Or maybe sick people sleep a lot. It is likely the causation is the other way around. While TFA is quick to say that the sleeping causes the deaths, the study itself only says they are "associated".
Actually, the STUDY explicitly says exactly what you just did about causation. From the Discussion section:
It is biologically plausible that short sleep duration may increase mortality risk through adverse endocrinologic, immunologic, and metabolic effects [48,49,50] or through chronic inflammation [47,51,52]. The mechanism for the association between long sleep duration and mortality is not well understood [17,47]. Most studies suggest that long sleep duration tends to be associated with sleep fragmentation, fatigue, depression, and underlying disease and poor health [53]. Therefore, the observed association between long sleep duration and all-cause mortality could be due to "reverse causality" or residual confounding [17,54]. An interesting observation from the current study is that risk combinations involving long sleep duration, prolonged sitting, and/or physical inactivity tended to be among those with the strongest associations with mortality, with HRs ranging from 2 to above 4. These associations remained significant and of similar magnitude after excluding deaths within the first 2 y of follow-up (S2 Table). This may suggest that the underlying characteristics associated with such behavioral patterns involving long sleep, sedentariness, and inactivity, perhaps not limited to major occult disease or failing health, may have contributed to the elevated risk for morality.
And they also note a few other things, like the fact that the "long sleep" problem tends to be a better marker for bad things with older people. This study didn't control for the fact that older people tend to sleep less or at least have trouble sleeping in longer blocks (compared to younger people). So it makes some intuitive sense that when you have an older person who also sleeps really long, it may be associated with some other problem (depression, disease, etc.), which is more likely to lead to a greater mortality.