Based on two surveys 11 years apart headed up by Dag Neckelmann of Haukeland University Hospital in Norway. Reuters article. Via Spikol. Insomnia at time 1 predicted anxiety disorder at time 2, but not depression, although depression and insomnia co-occurred.
I thought the fact that it wasn’t significantly predicting depression (despite predicting anxiety) was pretty interesting, since insomnia and depression are widely known to be related (and anxiety and depression can both co-occur and each cause the other). Maybe insomnia is a byproduct of early anxiety that isn’t yet diagnosable? Maybe it’s a version of the same phenomenon where lack of sleep can make bipolar people hypo/manic?