In a recent US study of 1,815 disadvantaged mothers and their children, mothers who worked more than 35 hours per week were more likely to experience insufficient sleep compared with mothers who worked fewer hours, while children were more likely to experience insufficient sleep when their mothers worked between 20 and 40 hours.

Nonstandard work schedules—such as working evenings, nights, or weekends—were linked with an increased likelihood of insufficient sleep for mothers but not their children.

“The results highlight a potentially difficult balance between work and family for many disadvantaged working mothers in the United States,” wrote the authors of the Journal of Marriage and Family study.