Shift Work

Definition of shift work

The International Labour Office (International Labour Organization, 1990a) defines working in shifts as “a method of organization of working time in which workers succeed one another at the workplace so that the establishment can operate longer than the hours of work of individual workers.”

The European Council Directive 93/104 (1993) declares that “concerning certain aspects of the organization of working time, shift work shall mean any method of organizing work in shifts whereby workers succeed each other at the same work stations according to a certain pattern. Shift-worker shall mean any worker whose work schedule is part of shift work.”

Besides these definitions, in the scientific literature, the term “shift work” has been widely used and generally includes any arrangement of daily working hours other than the standard daylight hours (7/8 am – 5/6 pm).

In most cases, shift work is synonymous of irregular, odd, flexible, variable, unusual, non-standard working hours. 

Shift work is considered a risk factor for many health problems. It has many negative cognitive effects (e.g., learning and memory deficits, loss of attention and vigilance). In addition, rotating night shift work disrupts our circadian clocks which is associated with a higher probability of developing obesity, diabetes and cardiovascular disease.

Shift work can also contribute to strain of marital, family, and personal relationships.

Shift work disorder

Shift work disorder occurs when you have difficulties adjusting to a work schedule that takes place during a time which most people sleep. When you have shift work disorder, there is a conflict between your body’s circadian rhythms and your work schedule. You may have to be at work when your body wants to sleep. Then when you have to sleep, you body expects to be awake.

People with shift work disorder may sleep up to four hours less than the average worker. Shift work disorder causes you to have trouble sleeping or be severely tired. The quality of sleep may be poor, and you may wake up feeling unrefreshed. You may feel fatigued or exhausted. This can hurt your performance at work, and can put you at risk for making a costly mistake or getting injured on the job.

Not everyone who does shift work has shift work disorder. Many people have difficulty initially adjusting to a new shift. If after several weeks you have difficulty falling asleep or staying asleep or you feel tired even after sleeping 7-8 hours, you may have shift work disorder.

The symptoms of shift work disorder usually last as long as you keep the shift work schedule. The sleep problems tend to go away once you begin sleeping at a normal time again. Some people may have sleep problems even after the shift work schedule ends.

Shift work disorder is a circadian rhythm sleep disorder. Your circadian rhythms are your body’s internal clock that signals when you are supposed to feel sleepy or alert. Your circadian rhythms operate on a roughly 24-hour schedule. Your body uses sunlight to determine how much of the sleep-promoting hormone melatonin it produces. In shift work disorder, melatonin production may occur when you need to be awake and alert for your job. Exposure to sunlight may prevent you from producing melatonin when you are supposed to sleep.

There are several variations of shift work schedules that can cause difficulties. This includes:

• Early-morning shifts
• Night shifts
• Overnight shifts
• Rotating shifts

Some people have a more difficult time with certain shift work schedules. Night owls may adjust more easily to working an evening shift than morning-types. Likewise, morning larks may have an easier time with early morning shifts. Many people have difficulty adjusting to overnight or rotating shifts.

Shift Work - Symptoms & Risks

Shift work disorder makes it difficult to get enough sleep each day. As a result, you may experience:

• Excessive sleepiness
• Difficulty falling asleep or staying asleep
• Lack of energy
• Difficulty concentrating
• Headaches
• Poor mood & irritability

Shift work disorder can also increase the risk for:

• Work-related injuries
• Costly mistakes at work
• Increased use of sick time
• Accidents related to drowsy driving
• Substance abuse due to use of drugs or alcohol to improve sleep

Increased long term health risks include:

• Frequent infections, colds and the flu
• Breast and prostate cancer
• High cholesterol levels
• Heart disease
• Obesity

Shift Work - Self Test & Diagnosis

Do you have a schedule that requires you to work when you would normally sleep?

Do you have trouble sleeping or are severely tired due to your work schedule?

Have you had this work-related sleep problem for at least one month?

Does this problem hurt your social, family or work life?

If your answer is yes to each of these questions then you might have shift work disorder. A board certified sleep medicine physician can provide you with methods to help your body adjust to your work schedule and to improve your sleep.

Before your appointment, the doctor will ask you to keep a sleep diary for two weeks. You will record when you go to sleep and when you wake up, along with how long you were awake due to difficulty sleeping. A sleep diary will help your sleep medicine physician see your habits and give them clues on what course of treatment to take. The physician will need to know your complete medical history. Be sure to inform him or her of any past or present drug and medication use.

Normally, a record of your sleep patterns and your work schedule is enough information. If the physician suspects other sleep disorders are causing your problems, you may have an in-lab sleep study or a multiple sleep latency test (MSLT).

Shift Work - Treatment

Bright light therapy

This involves exposure to a special artificial light at certain times to help reinforce your body clock and ease the transition to a new time zone. Schedule short sessions when you first wake up and midday. You can use a special light box, desk lamp, visor or dawn simulator for light therapy.

Sleep medications

Your doctor can prescribe for you a sleeping pill to help you get rest at the proper times. Sleeping pills may help you sleep better in the short term. Over a length of time you may develop a dependency or a tolerance. Many people also experience side effects when on sleep medications.

Melatonin

Melatonin supplements may help you adapt better to a shift work schedule. Melatonin is a natural hormone produced by the brain’s pineal gland and considered a signal for when you body is supposed to sleep. Research suggests that a dose of 0.5 mg is just as effective as higher doses. Take melatonin several hours before you plan to sleep.

You can also follow these sleep tips:

• If you work rotating shifts, ask your manager to schedule a clockwise rotation. This means that your new shift will have a start time that is later than your last shift. It is easier to adapt to this type of rotation because it is easier to stay up late than to go to bed early.
• If possible, take a nap during a break in your shift or before reporting for a night shift. Even a nap of just 20 to 30 minutes can improve your alertness on the job
• Arrange for someone to pick you up after a night shift, or take a bus or cab home. Drowsy driving can put your life and the lives of other drivers at risk
• Try to keep the same schedule on work days and days off. Keeping a routine helps your body know when to be alert and when to sleep
• Plan ahead for a major change in a shift-work schedule. Begin to alter your sleep time a few days in advance. This will make it easier for your body to adjust. See the example below
• Use moderate amounts of caffeine to help you stay alert on the job. Stop drinking coffee in the later portions of your shift so that it does not disrupt your sleep when it is time to go to bed.
• Avoid exposure to sunlight if you need to sleep during the day. Wear sunglasses if you must go outside.
• Make sure others in your home are aware of your work schedule. They should keep the home quiet when they know that you need to sleep