Retail workers’ unpredictable schedules affect sleep quality: Evidence from the Gap

Policymakers, advocates, and researchers are increasingly paying attention to the role work schedules play in the lives of low-wage workers. They find that regular, predictable schedules are rare in the retail field. In fact, typical retail workers have little input into their hours, receive fewer than three days’ notice of their schedules, and face canceled shifts and wide variation in their schedules from week to week.

Recently released research conducted in the retail outlets of The Gap, Inc. adds to the evidence base by shedding light on surprising connections between retail workers’ schedules and their sleep patterns. The researchers find that poor schedules translate to poor sleep. In turn, other research suggests that poor sleep translates to poor health and subpar work performance.

The research was conducted by Joan C. Williams of the University of California Hastings College of the Law, Susan Lambert of the University of Chicago School of Social Service Administration, and Saravanan Kesavan of the University of North Carolina Kenan-Flager Business School. Their research is co-funded by the Washington Center for Equitable Growth.

To increase Gap workers’ control over their schedules and their schedule stability, the study authors designed a novel, multicomponent intervention. The intervention included:

• App-based shift swapping
• Standardizing start and end times of shifts
• Funding for extra shifts when stores were understaffed
• Increased consistency for workers’ schedules from week to week
• A “part-time plus” group of workers, who received a soft guarantee of at least 20 hours per week

The researchers then randomly assigned 19 stores to a treatment group to implement the intervention and nine stores to a control group that did not implement the intervention.

The Gap was so committed to increasing the amount of notice workers had of its scheduled shifts that the company extended two components that were originally planned to be part of the intervention—two-weeks advance notice and the elimination of on-call shifts—to all of its workers in North America prior to the beginning of the experiment. So, this experiment tells policymakers and businesses alike how the multicomponent intervention affects workers’ lives beyond advance notice alone.

The researchers compared the experiences of workers in the treatment and control stores and found that the intervention improved the consistency and predictability of workers’ schedules. Perhaps more surprisingly, the researchers found that the intervention made a substantively (and statistically) significant impact on the sleep quality of workers who received the intervention.

After the intervention was implemented, the researchers compared the self-rated sleep quality of workers in the treatment stores and the control stores. Controlling for worker demographic characteristics and sleep quality in control and treatment stores prior to the intervention, the study team found that the scheduling intervention improved sleep quality by 6 percent to 8 percent.

Why is this surprising? Some scheduling practices—such as working “clopening” shifts, in which a workers may have fewer than eight hours between a closing shift at night and an opening shift the next morning, or working nonstandard overnight hours—seem to obviously interfere with a worker’s ability to sleep. But this intervention aimed to generally affect the stability and predictability of workers’ schedules and to increase workers’ control over their schedules. The intervention did not specifically seek to reduce clopening and nonstandard shifts—the most obvious culprits behind poor sleep.

So, what might be driving these impacts? One Gap worker interviewed by the research team described how fluctuating schedules prevent workers from establishing the regular circadian rhythms that people need in order to fall asleep. She remarks: “Myself and my counterpart have to completely swap our sleep schedules every two days and it really takes a toll on our lives outside of work and ability to sleep for the next day.”

Similarly, when workers are called in unexpectedly to work during their normal sleep hours, this affects sleep quality. Another Gap worker described a last-minute twilight shift: “Friday, we added three extra bodies to get a shipment done. I had four of us come in at 3 a.m. Our little army was sleepy.” To have consistent time for sleep, people need consistent schedules.

These findings are echoed in nonexperimental work. Sociologists Danny Schneider at the University of California, Berkeley and Kristen Harknett UC San Francisco find that workers who do not work on-call shifts are 8 percentage points more likely to report good quality sleep than those who do.

This suggests that the findings from the Gap underestimate how much scheduling interventions could affect sleep quality among retail workers. Remember: Neither workers in the treatment nor the control stores worked on-call shifts, and workers in both groups of stores received two-weeks advance notice of their schedules. For workers with little advance notice of their schedules and for those who work on-call shifts, increases in stability and predictability could translate into even more sizeable gains in sleep quality.

Why does sleep quality matter? Adequate nightly rest is not a luxury good for people in search of radiant skin. Sleep is essential to heart health, hormone regulation, and psychological well-being. When inadequate sleep is a chronic condition, it can lead to obesity, diabetes, and infection. Beyond sleep’s importance for worker health, sleep also matters for job performance. Sufficient sleep is linked to better cognitive processing, while low sleep quality is linked to irritability.

To perform their jobs well, retail workers need to troubleshoot in real time and display patience and kindness in interactions with customers. Consistent with the importance of sleep for labor productivity, in related work the study team found that their intervention also affected business’ bottom line. In treatment stores, labor productivity grew, and profitability increased by a remarkable 7 percent.

The Gap study shows that by improving the quality of workers’ schedules, businesses and policymakers can simultaneously stimulate the U.S. economy and improve workers’ health. Indeed, cities and states are increasingly seeing the value in requiring employers to raise the floor on schedule quality. New York City, San Francisco, Seattle, Philadelphia, Emeryville, California, and the state of Oregon have all passed legislation that has a similar goal to the Gap intervention: to provide workers with more control over their schedules and to ensure that schedules are more predictable. Rigorous academic research increasingly suggests that retail workers in these jurisdictions will be sleeping a little more soundly and working a little more productively.