This article finds another link between higher overall functioning in life, and better sleep. In this case, the researchers were examining the relationship between the level of marital happiness in women, and the quality of sleep. The results suggest (at least for Caucasian women), that a happier marriage is related to better sleep.
Again, I have to admit this isn’t all that surprising, except for the fact the results may not apply to women of color. Sleep is often effective as a sort of “Life Satisfaction Barometer,” in that the better you are functioning, the better you sleep, and vice versa. I would imagine, for example, people would rate their marriages better if their sleep improved. In some cases, sleep is the chicken, in other cases, the egg; in some cases we don’t know. But in any event, improving sleep generally helps someone do better in general, and doing better in general helps someone sleep better at night.