People who work night shifts often have trouble re-acclimating to a day schedule on their days off. Shift work can seriously disrupt a person's circadian rhythm, the normal sleep-wake cycle. As many as 32 percent of night shift workers and 26 percent of people who rotate shift experience shift work disorder, or SWD, lead author Robert Sack, M.D. reported in 2007 in "Sleep." Shift work can cause decreased alertness and reaction times that may improve with bright light therapy, Science Daily reports.
Purpose
The purpose of bright light therapy in shift workers is to improve sleep while off work and alertness and productivity while at work by exposing the worker to lighter brighter than normal household lighting during prescribed periods during the day or night.
Methods
Several methods to supply light therapy exist. A light box can supply as much as 10,000 lux of light, the American Academy of Sleep Medicine reports. A person sits about 18 to 24 inches from the box for a period of as little as 15 to 30 minutes. Light visors that allow the wearer to move around can supply between 3,000 to 10,000 lux. Special light therapy desk lamps that look like regular furniture can also be used for bright light therapy. A physician or sleep specialist must prescribe the time period allowed under the light and the time of day of use. Usually people who work nights use the light box in the evening before going to work, the AASM advises. Wearing dark goggles or special sunglasses to block daylight when trying to sleep increases the effectiveness of light therapy for shift workers.
Side Effects
Light therapy can cause side effects. Typical side effects include headache, eye strain, nausea, vomiting, agitation, irritability, fatigue and dry mouth, according to MayoClinic.com. Moving farther away from the box, reducing treatment time or changing the time of day the box is used can help reduce annoying symptoms, MayoClinic.com adds. Starting therapy slowly and using a humidifier can also help reduce side effects, the AASM states.
Results
Light therapy can help improve sleep and nighttime alertness within a few days, although full effects of light therapy can take several weeks, MayoClinic.com reports. While completely adjusting to a night schedule, even on days off, best improves nighttime alertness, most workers want to stay awake during the day on days off. Researchers at Rush University Medical Center found that "compromise circadian phase position", with adjustments between day and night rhythms through use of light exposure, dark sunglasses and a strict sleep schedule helped increase productivity for night workers.
Considerations
Some light boxes don't filter out UV light, which can cause skin and eye damage, particularly in people who take medications that increase light sensitivity or those whose eyes are especially light sensitive, MayoClinic.com warns. Light therapy may also trigger mania episodes in bipolar patients.
References
- MayoClinic.com: Light Therapy
- American Academy of Sleep Medicine: Bright Light Therapy
- Ergonomics Today: Study Explores Light Therapy to Ease Night-Shift Workers' Fatigue
- Science Daily: How Shift Workers Can Improve Job Performance And Implement Realistic Sleep Schedule
- "Sleep": Circadian Rhythm Sleep Disorders, Part I; Robert Sacks, MD et al; 2007
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