The study which explored the impact of potential mediators, such as children's sleep and dietary habits, the amount of time they spent watching TV and family mealtime routines, found that kids whose mothers worked full time got fewer hours of sleep than peers whose mothers worked less than 20 hours per week. The children of women who worked full time also tended to have higher BMIs at the second weigh-in.
Lead author Katherine E. Speirs, a postdoctoral research associate in human and community development at the University of Illinois, said that just 18 percent of the preschoolers in the sample were getting the 11 to 12 hours of nightly sleep recommended by the National Heart, Lung and Blood Institute.
It was also found that on average, the children were getting about 9.6 hours of nighttime sleep. Each additional hour of nighttime sleep that a child obtained was associated with a 6.8 percent decrease in their BMI at the second weigh-in.
The researchers said that they think it might be the more hours that mothers are working, the less time they have, the more they think about whether spending quality time with the kids or getting to bed early. And then in the morning, when mothers leave for work, their children also wake up early to get to day care.
The study was published online in the journal Sleep Medicine.