Shift work -- working off-hours such as evenings and nights, or rotating schedules -- can play havoc with your body’s systems, according to a December 2009 article in “U.S. News and World Report.” Your circadian rhythm, or internal clock, is disrupted by the differences in sleeping patterns, which can affect your health. In addition to peptic ulcers, cardiovascular disease, cancer, obesity and diabetes, shift work has been linked to depression.

Depression and Sleep

Depression affects at least 20 million Americans, according to the National Sleep Foundation. Sleep and depression are clearly related to one another, but it may be hard to determine whether lack of sleep causes depression or depression causes sleep problems. Sleep problems, however, are more likely to be associated with severe depression, according to the NSF. Night shift workers may suffer from sleep deprivation because they cannot sleep during the day, their sleep is disrupted or they have inconsistent sleep patterns. Oddly, however, a night of partial or complete sleep deprivation may actually improve depression in some people, according to the NSF, though the reasons are obscure.

Shift Work and Social Isolation

Those who work the night shift are on a different schedule from the rest of the world, and that may include their families and friends. The American College of Emergency Physicians notes that those who work night shifts may experience social isolation. Social isolation has also been implicated as a risk factor for major depression, according to a July 2009 article in “Psychology Today” by Stephen Ilardi, a psychologist and author of “The Depression Cure.” ACEP also notes that among emergency physicians, an increased divorce rate may be related to shift work.

Sleep Disorder and Depression

Shift work sleep disorder, or SWSD, can occur in those who work non-traditional hours -- roughly 10 p.m. to 6 a.m., according to the My.ClevelandClinic.com website. The clinic notes that shift workers tend to become progressively more sleep deprived when they work several nights in a row. Shift workers with SWSD develop a pattern of recurring sleep disruption, with symptoms of either insomnia or excessive sleepiness. Other symptoms include headaches, lack of energy, and mood disorders such as depression and irritability.

Suggestions for Shift Workers

Some professions require shift work, such as emergency medicine or nursing, police work and other emergency or lifesaving services. If you are a shift worker, try to establish routines that allow you to get at least seven to eight hours of sleep each day. Darken your room with blackout curtains or heavy shades, use earplugs or white noise from a fan, and avoid caffeine, alcohol and nicotine. Try to keep your schedule consistent, as switching to a normal daytime routine on your days off can increase your risk of problems, according to “U.S. News and World Report.” If possible, take a nap before going to work. If your depression continues or becomes severe, consult a physician.