Shift Work Disorder

Learn About Shift Work Disorder

Shift workers are required to be awake when the majority of people are asleep, and vice-versa.  This puts their sleep/wake cycle at odds with day/night cycle.  Further complicating matters is that they are frequently awake during their sleep period due to social demands that can only be met during daytime hours.  The net effect is being chronically sleep deprived and worse, being sleep deprived at one of the physiologically least favorable portions of their sleep/wake cycle; therefore they need to be cautious when driving and when in environments in which dozing off is dangerous. Using drugs or alcohol to try to improve sleep can lead to substance abuse.

While it is theoretically possible to train the sleep/wake cycle to reverse itself relative to the day/night cycle, this requires quite a bit of discipline and rarely happens.  Therefore these workers are awake when their body wants to sleep, and must sleep when the body wants to be awake.  This leaves them less than optimally alert during their shift.  If the shift schedule causes sleep that is fragmented and non-restorative, resulting in daytime sleepiness and impairment in functioning for at least a month, then Shift Work Sleep Disorder is a likely diagnosis.  Other features of Shift Work Sleep Disorder include headaches, difficulty concentrating, and low energy levels.

Improving the sleep in Shift Work Sleep Disorder requires understanding how the circadian clock works (see Sleep Disorders III:  Disorders of Sleep Rhythm) and finding ways to adjust the circadian rhythm as best as is feasible under these unnatural work conditions. Adjusting the internal clock to adapt to a reversed day/night activity schedule may include properly timed bright and dim light exposures relative to the timing of the desired sleep period. For example, an individual whose shift ends in the morning who intends to go home and sleep should minimize exposure to light between the end of work and bedtime (e.g., wear sunshades, have blackout curtains in the bedroom).  Medication is available to help shift workers maintain alertness during their shift, and allow them to remain awake so they can bring more of the urge to sleep (sleep pressure) to their sleep period.  

Young adults and “night owls” find it easier to adjust to night and non-traditional work shifts.  They feel that they function better at night; they often go to bed late on a regular basis. These people may choose to work a night shift; they prefer to work during the hours when they feel the most alert.

Normally, a record of sleep patterns and work schedules is enough information for a doctor to diagnose Shift Work Sleep Disorder.  additional tests may be required if other sleep disorders are suspected to be causing the symptoms, such as an overnight sleep study conducted at home or in the sleep lab (polysomnography) or a daytime nap study (the Multiple Sleep Latency Study, (MSLT)) that records sleep onset during four naps taken throughout the day. It also shows the kind of sleep obtaining during the nap, particularly if rapid eye movement (REM) sleep occurs, as this has diagnostic significance for the condition of narcolepsy.  

There are some steps that can be taken to minimize the risk of developing Shift Work Sleep Disorder.  Maintaining a strict sleep-wake schedule, even on days off from work, is the ideal way to harmonize the sleep/wake cycle and the day/night cycle.  Avoid frequently rotating shifts; but if they must rotate it is more physiologic that they rotate forward rather than backward, to increase the probability that the sleep/wake cycle will synchronize with, or entrain, the rest/activity cycle.   While working the night shift, it is important to minimize or avoid stimulants such as caffeine during second half of the shift, since this can prevent being able to initiate or maintain sleep once going to bed. Although keeping the work environment well lit with bright light can help maintain alertness while working at night, avoid bright light exposure prior to going to bed since it will interfere with the initiation and maintenance of sleep.  Wear sunglasses during the drive home to avoid exposure to bright morning light.  Keep the bedroom dark and quiet so that it is conducive to sleep.  Most importantly, do not drive a motor vehicle, operate dangerous machinery, or otherwise engage in potentially hazardous activity while impaired due to sleepiness. - Mark J. Woyshville, MD

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