The poor manage to spend the most time in bed and yet get the least actual sleep due to long “sleep latency,” the time spent in bed trying to fall asleep. I’ve got a fairly downscale sleep profile. I’d like to see some further research on this. In the United States, it’s always interesting to look at class issues through both the income lense and the education lense and see which has more explanatory power. Age, marital status, and whether or not you have children also seem like obvious demographic factors to look at. Personally, I find that a lot of my best work gets semi-done during periods of sleep latency, in that that’s often when I figure out what I’m going to write the next day. Is that genuinely inefficient?