In the first study, researcher Michael D. Nevarezat of Harvard Medical School found that
..infants' mean sleep duration at six months, including daytime naps and nighttime
sleep, was 12.2 hours per day. Less household income and lower maternal
education were associated with shorter infant sleep duration.
Compared with Caucasian infants, African-American infants slept 0.94 fewer total hours per
day. Also, African-American, Hispanic, and Asian infants slept more hours during
daytime naps but fewer hours at night. Infants whose mothers had a history of
depression during pregnancy and those who were being breast-fed at six months
appeared to sleep fewer total hours per day.
* * *As with other complex pediatric conditions such as obesity, the amount of sleep children obtain, even during infancy, may have larger socioeconomic and cultural contexts that warrant consideration.
NB. It would have been interesting to see how the sleep patterns of infants and mothers correlate...
In the second study, researcher Molly Countermine, of Penn State University, focused on 45 families with infants between one and 24 months, and found adaptation (measured by parents' satisfaction with infants' sleep location, and bedtime and nighttime behavior) was poorer when infants spent any part of the night with their parents. That was true even when parents endorsed bedsharing.
It suggests that when infants are close at hand, parents presumably get less sleep, which does not seem to be a good mix.
[Interestingly, there is an Associated Professional Sleep Societies (APSS)].
NB. More research about the quality and quantity of parental sleep, and the effect that sleep deprivation has on the behavioral control of parents, would really be interesting. And useful.