A person's volatile work schedule can affect sleep and make them feel tired. But can they have a long-term health effect? Researchers have found that working outside the typical 9–5 schedule in early adulthood can worsen a person's health by the age of 50.

Previous studies have shown how nonstandard work schedules can negatively impact physical and mental health. In the latest study published in the open-access journal PLOS ONE, researchers took a "life-course" approach to study the lasting health impacts of unpredictable work schedules. This means they analyzed how work patterns influenced health not just at one specific time, but throughout an individual's adult life.

The researchers defined a standard work schedule as 6 a.m. to 6 p.m., an evening work schedule as 2 p.m. to midnight, and a night shift as 9 p.m. to 8 a.m. Participants were considered to have "variable" schedules if they worked split or rotating shifts or had irregular hours.

The team used data from over 7,300 participants who were part of the National Longitudinal Survey of Youth, 1979. The participants were between the ages of 14 and 22 and were surveyed at various points over time. Approximately 50% of the participants were White, 33% were Black, and 19% were Hispanic individuals.

The researchers discovered that 26% of the participants consistently worked stable standard hours, while 35% primarily worked standard hours. About 17% started with standard hours in their 20s but later transitioned to volatile working patterns, which included evening, night, and variable hours. Another 12% started with standard hours and later switched to variable hours, while the remaining 10% were mostly not working during this period.

The results showed that transitioning from working early standard hours to volatile schedules between ages 22 and 49 was significantly associated with poor health outcomes. This also worsened their health and increased their risk of developing depressive symptoms at age 50, an effect similar to that of being educated only to below high school level.

The study also identified certain racial and gender-related trends in employment patterns and resultant adverse health consequences. For example, they noted that Black Americans had more chances to have volatile work schedules and associated poorer health.

"About three-quarters of the work patterns we observed did not strictly conform to working stably during daytime hours throughout our working years," said Dr. Wen-Jui Han, the sole author of the study and professor at the Silver School of Social Work at New York University.

"This has repercussions. People with work patterns involving any degree of volatility and variability were more likely to have fewer hours of sleep per day, lower sleep quality, lower physical and mental functions, and a higher likelihood of reporting poor health and depressive symptoms at age 50 than those with stable standard work schedules," Han said.

Researchers believe that irregular sleep, fatigue, and emotional exhaustion because of a hectic work schedule might explain why they become more vulnerable to poor health. These effects can accumulate over a person's lifetime.

"Work that is supposed to bring resources to help us sustain a decent life has now become a vulnerability to a healthy life due to the increasing precarity in our work arrangements in this increasingly unequal society. People with vulnerable social positions (e.g., females, Blacks, low education) disproportionately shoulder these health consequences," Han added.