Sleep, and his brother

The Herald has a very good story on sleeping pils and increased rates of death.  The story describes the study design and the findings, names the journal, and even gives a link to the paper, which is  in an open-access journal.

The study itself is interesting: they looked at at 10,000 people who took sleeping pills, and about 23,000 who didn’t, from a large US healthcare system (about the 2/3 the size of New Zealand).  After matching as well as they could on other health factors, the researchers still found a much higher rate of death, 3-5 times higher, in people who took sleeping pills.

It’s not easy to think of a sufficiently-strong confounding effect to explain this — you would need a factor that increases people’s chance of taking sleeping pills at least 3-5 times and also increases their rate of death at least that much. One possibility is sleep disturbance itself — it could be that needing sleeping pills is the risk factor, and the pills themselves are relatively innocent.

One factor that, I think, does cast a bit of doubt on the results is that the associations were about the same for all classes of sleeping pills:  the traditional benzodiazepines, the new short-acting drugs such as Ambien, and sedating antihistamines.   It’s entirely plausible that they all have adverse effects, but it’s a bit surprising that the effects would be so similar.