> "Another study from the same NIMH group has found that, among severely depressed subjects, spending more time awake between 4 a.m. and 5 a.m. (as measured by a sleep study called polysomnography) is linked to increased risk of suicidal thinking the next day."

I wonder if something more general could be inferred - when I'm getting bad sleep (stress-related, mostly), I tend to wake up at around 4AM. My day is often cranky, sometimes I'm completely ineffective until noon.

Could overall sleep levels be more coincident with lower suicidal thoughts?