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Shift Work Sleep Disorder
Cause – Symptoms – Treatment – Prevention – Light Therapy – Melatonin – Work Schedule Adjustments – Scheduled Naps – Provigil – Nuvigil
Shift Work Sleep Disorder
Night shift and very late/very early shift workers are forced to sleep during unconventional time. Shift work sleep disorder causes poor sleep quality and/or insufficient quantity of sleep leading to chronic sleep deprivation.
A fixed night shift is generally easier to adapt to. Alternating shifts are tolerated worse because the internal body clocks have to be constantly readjusted.
Sleep-wake cycle is one of the numerous processes that follow circadian pattern. Those circadian rhythms are described on the sleep physiology page. Day light is an important regulating factor of the sleep-wake cycle. Shift workers, however, often have to sleep during the daytime. Besides, an individual sleep pattern goes out of sync with the rest of the society. In spite of those obstacles, it is still theoretically possible to make appropriate arrangements and sleep during unconventional time.
The problem comes with variable sleep schedule that occurs either due to alternating shifts or due to switching to night sleep on the days off. Variable sleep time leads to disruption of normal 24 hour circadian rhythm. As a result, normally synchronized multiple circadian rhythms run independently of sleep wake cycle. Level of alertness, body temperature, blood pressure, hormone levels, pain perception, and many other activities are circadian rhythm dependent. Even some of our genes – clock genes – are normally activated and shut down during specific times.
Irregular sleep pattern messes up with the internal clocks and has a significant impact on the whole body. Since multiple circadian rhythms have a mutual influence on each other, the eventual outcome of irregular sleep schedule are poor sleep quality, along with other symptoms of chronic sleep deprivation – fatigue, difficulty concentrating, anxiety, depression, headaches, dizziness, etc.
Symptoms of Shift Work Sleep Disorder
Typical complaints in shift work disorder are difficulty staying alert while at work and difficulty falling asleep.
Other symptoms include anxiety, depressed mood, fatigue, malaise, chronic headaches, dizziness, decreased libido and digestion troubles. The risk of high blood pressure, heart disease, and weight change are increased. The rate of drug and alcohol abuse is increased among shift workers.
While people working overnight shifts have more severe symptoms than late night shifts, alternating shifts pattern is even worse.
Overall, shift work disorder leads to less than normal sleep hours and chronic sleep deprivation. The obvious cause of this disorder is a mismatch between the internal clocks and the activity pattern, since shift workers have to stay active at the times when level of alertness is low, while the sleep time may fall onto the period of maximum alertness.
Night shift workers may have no difficulty falling asleep during the daytime but maintaining an adequate amount of sleep is difficult. As a result, the actual number of sleep hours becomes insufficient. Reverting to conventional sleep time on the days off creates even more mess.
Treatment of Shift Work Sleep Disorder
Radical treatment is challenging. It is not practical to adjust internal clock settings on demand.
Adjustments to Work Schedule
Whenever possible, alternating shifts are better to be avoided. Another option is to set the shift rotation in such a way that the sleep time for the following shift is delayed rather than advanced.
The rational for this is the fact that most people have internal clocks set for 25 hour cycle. Adaptation to delayed sleep time goes faster (1.5 hours per day) vs. advanced bed time (1 hour per day).
No matter what you do, however, rotating shifts produce a state of persistent re-adaptation of internal clocks.
Brief naps prior to work time and during break times improve alertness levels during work hours. The naps have to be short (10 to 20 minutes). Longer naps may cause fatigue and decreased concentration while at work.
Light therapy is helpful for internal clock adjustments. Maintaining bright light at work, using sunglasses during morning commute, and darkening the room during sleep time accelerate internal clock adaptation. These measures are proven to elevate the level of alertness at work and to improve the quality of sleep.
Melatonin, taken before bed time, improves daytime sleep but it does not improve alertness at night. The dose of Melatonin must be low (about 0.3 mg). Higher doses stay in the system for too long.
Caffeine may improve alertness at night. Provigil (Modafinil) and Nuvigil (Armodafinil) are wake-promoting agents. Taken shortly before the night shift, they improve performance at work.
Chronic use of medications should be discouraged.
Sleeping pills are not effective for shift work disorder.