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Shift Work

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What is it?

Shift work sleep disorder is a circadian rhythm sleep disorder that occurs due to a work schedule that takes place during the normal sleep period. This schedule requires you to work when your body wants to sleep. Then you have to try to sleep when your body expects to be awake. The timing of when you sleep and wake is much different than what your internal body clock expects.

This clock controls the “circadian rhythms” in your body. The word “circadian” means to occur in a cycle of about 24 hours. These rhythms make you feel sleepy or alert at regular times every day. Your internal clock tells your body when it is time to sleep at night. It also tells your body when it is time to be awake during the day. Among other factors, your clock is “set” by your exposure to sunlight.

There are several types of shift work schedules. These include the following:

  • Night shifts
  • Early-morning shifts
  • Rotating shifts

This sleep problem causes you to have trouble sleeping or to be severely tired. It is most often reported due to the night and early-morning shifts. These workers typically sleep one to four hours less than average. They also feel that the quality of their sleep is very poor. They do not feel refreshed when they wake up. This can hinder their performance at work. It can also make them less alert. This can put them at risk of an injury on the job.

The condition usually lasts as long as you keep a shift work schedule. Once you begin sleeping at a normal time again, the problems tend to go away. In some people, the sleep problems may continue even after the shift work schedule has ended. The length and severity of the problem varies from person to person. Some people are able to adjust better than others. There are also many different types of work schedules. Some people may only work an overnight shift to cover for a co-worker. Their sleep problem would be very brief. Others may work a regular night shift. Their problem would be ongoing. Many shift workers also work more hours each week than the average person. This can add fatigue to their sleep problems.

Many early-morning work shifts start between 4 a.m. and 7 a.m. These shifts may cause you to have trouble falling asleep or waking up. Those who work a regular evening shift may also have a hard time falling asleep.

Those who work night shifts are likely to become very tired on the job. They may feel a strong urge to take a nap. They also may not think clearly because of a reduced level of alertness. They are more likely to make mistakes.

They tend to sleep during normal nighttime hours on weekends or days off. This makes it even harder for their bodies to adjust to the unusual work hours.

This disorder can also affect you away from the job. You may need to use major portions of your free time to catch up on sleep. This can have a negative impact on your social and family life. You may also be more irritable. This can hurt your relationships with others. The disorder also increases the risk of drowsy driving. This can lead to an auto accident as you drive home from work. The disorder may also make stomach or heart disorders worse. Using drugs or alcohol to try to improve sleep can lead to substance abuse.


Who gets it?

Sleep problems from shift work affect male and female workers of all age groups. Those who have unusual work hours are most likely to have it. Estimates are that 2% to 5% of the general population is affected. This estimate does not include people who work early-morning shifts.

Some people feel that they function better at night. They go to bed very late at night on a regular basis. They may have delayed sleep phase disorder. These people may choose to work a night shift. They prefer to work during the late hours when they feel that they are more alert.


How do I know if I have it?

1. Do you have trouble sleeping or are you severely tired?

2. Is this problem due to a schedule that requires you to work when you would normally sleep?

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

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

If your answer to each of these questions is yes, then you might have shift work disorder.

It is also important to know if there is something else that is causing your sleep problems. They may be a result of one of the following:

  • Another sleep disorder
  • A medical condition
  • Medication use
  • A mental health disorder
  • Substance abuse

Do I need to see a sleep specialist?

You may have to keep unusual work hours for a long period of time. In this case, you may want to visit a sleep specialist. He or she can provide you with methods to help your body adjust and to improve your sleep.


What will the doctor need to know?

You should complete a sleep diary for two weeks. This will give the doctor clues as to what might be causing your problems. You can also rate your sleep with the Epworth Sleepiness Scale. This will help show how your sleep is affecting your daily life. The doctor will need to know your complete medical history. Be sure to inform him or her of any past or present drug and medication use.


Will I need to take any tests?

Normally, a record of your sleep patterns and your work schedule is enough information for the doctor. He or she may want to use additional tests if other sleep disorders are suspected to be causing your problems. One or both of the following sleep studies might be considered:

1. Overnight Sleep Study

Also called a polysomnogram, this study charts your brain waves, heart beat, and breathing as you sleep. It also records how your arms and legs move.

2. Multiple Sleep Latency Test (MSLT)

This is a daytime nap study that records brain waves during at least four naps. The MSLT measures how fast you fall asleep during the day. It also shows what kind of sleep you have when you take a nap.

Your doctor may ask that you take a test to screen for drugs before you have the MSLT. There are a number of drugs that can affect the results of the sleep study. The drug screen will help the doctor to know what the MSLT really says about your sleep problem.


How is it treated?

Many employers have plans to help their shift workers stay better rested. The goal is to lessen the effects of shift work on the workers’ body clocks. This keeps them healthier overall, as well as safer on the job. Some of the techniques used by employers include the following:

  • Reducing the number of times a worker changes shifts
  • Changing shifts forward in time instead of backward
  • Giving the workers regular rest periods
  • Offering employees the option of exercise breaks
  • Using bright light to imitate sunlight

More Information
Sleep tips for shift workers from the American Academy of Sleep Medicine

Reviewed by David A. Kristo, MD
Updated July 10, 2007



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