For the millions of Americans who work “nonstandard” shifts – evenings, nights or with rotating days off – the schedule can be especially challenging with children at home.

But a new study from the University of Washington finds that consistent hours, at whatever time of day, can give families flexibility and in some cases, improve children’s behavior.

The study, first made available online in December 2017 before being published in the June issue of the Journal of Family Issues, focuses on two-parent families in which one parent works a nonstandard shift, hours that are common in health care, law enforcement and the service sector. The study finds that the impacts of parent work schedules on children vary by age and gender, and often reflect which shift a parent works. Rotating shifts — a schedule that varies day by day or week by week — can be most problematic for children.

“Workers often struggle to carve out the work/life balance they want for themselves, and in dual-earner families, balancing partners’ schedules remains an issue for many families,” said Christine Leibbrand, a graduate student in the UW department of sociology and author of the study. “Parents are facing these decisions of balancing work and caring for their children.”

There are conflicting figures on the number of people who work nonstandard shifts. In 2004, the Bureau of Labor Statistics counted nearly 15 million such workers, up from 14.5 million in 2001, when one in seven people worked a nonstandard schedule. A 2014 study by the National Bureau of Economic Research estimated as many as one in four Americans worked a night shift. Increasingly, other factors may influence who works when: rapidly changing technology affecting many industries, the increase in working remotely, and the growing gig economy.

Nonstandard schedules, especially for single-parent and lower-income families, are associated with behavior problems among children, according to past research.

To add to that research, Leibbrand examined data on two-parent households in which one parent worked a nonstandard shift. On this, she was inspired in part by her own family: a sibling who’s a nurse, another a firefighter, both with children.

Using information from the National Longitudinal Survey of Youth, which started following a group of nearly 13,000 individuals in 1979, and its Child Supplement, which started following the children of those individuals in 1986, Leibbrand analyzed parents’ work schedules against their periodic reports of their children’s behavior. Child behavior (covering ages 5 to 15) was ascertained from a 28-question survey that covers issues such as anxiety, aggression and getting along with peers. Those results receive a Behavioral Problems Index score — the higher the score, the more problems a child is reported to have.

Among Leibbrand’s findings:

• A mother’s night shift tended to have benefits for boys and girls, especially when they’re young
• A mother’s rotating shift, or a split shift — say, going to work for a few hours in the morning, and again in the evening — was associated with greater problems among boys of all ages, and among older girls
• A father’s rotating or split shift was associated with more behavior problems among girls, particularly younger girls
• A father’s night shift tended to coincide with behavioral benefits among boys

What’s less clear is why.

The gender differences may relate to parent involvement. Some research finds that fathers tend to be more involved in their sons’ lives, perhaps explaining why fathers’ shift schedules are more likely to be associated with benefits for boys. Other research on the impact of shift work on adults’ physical and emotional stamina, Leibbrand said, suggests that parents who work nonstandard schedules may be under more stress and sometimes have less energy, or “psychological capital” to meet their child’s needs. Unstable shift schedules, like rotating shifts, could be especially stressful for parents. This stress may have important repercussions for children, as children learn to model their parents’ behavior.

Since most of the children aged out of the survey by 2006, how these issues may play out today is a question, too. Technology has transformed how children play and learn, as well as how adults work, increasing the numbers who work remotely while rendering some jobs obsolete. All of those trends could affect child behavior and a family’s quality of life, Leibbrand said.

But when it comes to nonstandard shift work, a consistent schedule — the same hours, on the same days each week — appears to buffer the negative effects, according to Leibbrand’s research. It provides consistency in child care, gives children more structure and allows the family to predict a parent’s availability for activities. A parent who regularly works the night shift, for example, may deliberately try to be awake and available for children before and after school, while the other parent handles dinner and bedtime routines.

But families don’t always have the resources for child care or control over work schedules. That’s where employers and policymakers come in, Leibbrand said. Solutions could involve allowing greater flexibility in the workplace or in providing paid family leave and access to quality child care.

“Most parents want to spend time with their children and want to find a way to do that,” she said. “We should be prioritizing people’s well-being and balancing of work and home life.”