How Your Work Schedule Affects Your Mood

Work in the United States has become a 24-hour phenomenon. Many workers, such as healthcare providers, must be available at all hours, and increasingly, companies are adding shifts to accommodate customers and vendors in different time zones.

Non-standard work schedules, which includes evenings, nights, weekends, and shift work are common. About 14 to 20 percent of Americans work non-traditional hours. However, these schedules often disrupt employees' sleep and may put workers at risk for mood disorders. Working irregular hours may also lead to shift-work disorder, a condition characterized by insomnia, excessive sleepiness during work, difficulties concentrating, headaches, and lack of energy.

Work Schedule and Biology

We have multiple internal rhythms, or biological clocks, that control critical body functions. Circadian rhythms, for example, regulate body temperature, the sleep-wake cycle, alertness, and many other life-sustaining activities. Circadian rhythms rely heavily on changes in light, so they are sensitive to irregular work schedules.

A non-standard work schedule or shift work can create a conflict between our internal clock and the actual time of day. The extent to which our circadian rhythms adjust to a new schedule determines how severely this schedule affects individual. On average, it takes about one week to adjust to an 8-hour shift change. Sleep changes may also disrupt our hormones, some of which are only secreted at night.

Furthermore, shift work may aggravate, or increase the risk of, developing mood disorders, at least in vulnerable individuals. Some studies suggest a high incidence of major depressive disorder during and after shift work. This risk is associated with the duration of exposure to the irregular schedule.

How to Cope

The study of biological rhythms on mental health is still a new field. There's a limited body of research, so we must be careful when interpreting study results. Given what we know so far, however, there are steps you can take to minimize potential negative mental and physical health consequences when you must work shifts or non-traditional hours.

  • Limit the number of night shifts you work to five or less, with days off in between. There is some evidence that permanent night shift does work well for certain individuals, especially those who are night owls or who work night shift by choice, rather than necessity.
  • Avoid working extended hours (more than eight daily) and long commutes.
  • Prepare your body for sleep as if it were bedtime to facilitate falling asleep during daylight hours.
  • Keep a regular schedule, even on the weekends.
  • Aim for seven to eight hours of sleep daily.


Marino, Patrick C. "Biological Rhythms as a Basis for Mood Disorders." Rochester Institute of Technology. Web. March 2005.

Woo, Jong-Min, MD, PhD, and Postolache, Teodor, T., MD. "The impact of work environment on mood disorders and suicide: Evidence and implications." International Journal of Disability and Human Development 7(2) (2008): 185-200. Web.

Shift work "Shiftwork Disorder News." Web.

Cleveland Clinic. "Shift Work Sleep Disorder." Web.