Shift Work - Health Consequences

Health Consequences

Shift work increases the risk for the development of many disorders, including:

• Shift work sleep disorder (SWSD): Shift work sleep disorder is a circadian rhythm sleep disorder characterized by insomnia and excessive sleepiness. Shift work is considered sine qua non for the disorder.
• Breast cancer A 2005 review of earlier studies came to the result that women whose work involve night shifts have a 50% increased risk of developing breast cancer. This may be due to alterations in circadian rhythm: melatonin, a known tumor suppressant, is generally produced at night and late shifts may disrupt its production. The WHO's International Agency for Research on Cancer listed "shiftwork that involves circadian disruption" as a probable carcinogen in 2007 (IARC Press release No. 180).
• Cluster headache
• Ischemic heart disease: Shift workers who had worked in that method for 15 years or more were three times more likely to develop ischemic heart disease.
• Fatigue
• Stress
• Poor sexual performance
• Appetite control: Shift work has been associated with a higher disposition for developing nutritional issues and obesity.

Shift work also can exacerbate symptoms and progression of chronic diseases, such as sleep disorders, digestive diseases, heart diseasee, hypertension, epilepsy, mental disorders, substance abuse, diabetes mellitus type 1, asthma, and health conditions that require medications with circadian changes in effectiveness.

UCSF neurologist Louis Ptacek, who studies circadian rhythms, genes and sleep behaviors, has been quoted: "It's not surprising, we have evolved on a planet that is rotating every 24 hours. Our internal clock is more than just when we sleep and wake. It's related to cell division and it regulates our immune systems. When we battle our internal clock, that has complications." Artificial lighting may additionally contribute to disturbed homeostasis.

The health consequences of shift work may depend on one's chronotype, that is, whether one is a day person or a night person, and what shift one is assigned to.

Many shift workers use stimulants such as caffeine to stay awake at work and/or sleeping pills to aid with sleep during the day. However, both are addictive and should be used with care. There is currently no research on shiftworkers and long-term use of sleeping pills.