SHIFT WORK

Using Light for Sporadic or Short Schedules

Rapidly changing shift schedules are most common, and they can causet long-term health related problems. The most helpful advice for fatigue managment and these shift workers is to receive a consistent schedule of light, regardless of the shift schedule. For example, if someone must shift schedules every few days, the best strategy would be to receive bright light before going and during the shift.

Going On Shift

New research shows that receiving a 30-minute burst of light before shift and then 15 minutes of light every 2 – 3 hours during shift not only increases alertness and performance, but shifts the body clock as well. Within three days, the body clock will have shifted to a night shift schedule. Taking time-release melatonin upon arriving home may accelerate shifting the body clock. After the second day, melatonin should not be necessary, and the body clock will have adapted to the new schedule. While working the night shift, it is important to wear sunglasses and avoid any bright light when going home.

Coming Off Shift

When coming off shift, one should not wear sunglasses, as it is now important to receive bright morning light. After arriving at home, the shift worker should use the light in the morning for approximately 30 – 45 minutes and he/she should wait at least three hours before going to sleep. After awakening, he/she may wish to use time-release melatonin in the early evening (4-7pm) to accelerate his/her body clock shift.

Cautions With Melatonin

One may want to wait a few hours after waking in the afternoon or evening before taking melatonin as it may cause drowsiness. Melatonin should not be taken if the person needs to drive or use heavy equipment. This routine should only need to be repeated once or twice before a normal sleep/wake schedule is achieved.

Cautions and Recommendations for Shift Work

The greatest difficulty people have with shift work is inconsistent schedules. Shifting circadian rhythms works best when a person only needs to shift every month or so. Constant rapid shifting is very difficult on the body. Shift workers often receive conflicting light signals at the wrong time for their shift. Constant exposure to conflicting light signals will weaken the circadian rhythm system and cause fatigue.
Using Light for Long-term Shift Schedules

Receiving bright light in the evening time while avoiding morning light will shift the body clock to a night schedule. The shift worker must first determine when he/she wants to wake up, and receive bright light at that time. Care must be taken to avoid any bright light when coming home from work and going to bed. This schedule should shift the body clock within a few days.

Accelerating circadian shifting with melatonin

Using melatonin in conjunction with bright light can accelerate shifting the body clock. A small dosage of melatonin (1 to 3 mg) can be taken approximately 12 hours after bright light is received. This can help move the body clock as much as four to six hours each day, in either direction.

Shifting from Day Schedule to Night

Because the circadian shift can be greater with melatonin, it may be easier to accelerate the body clock to the desired wake/sleep time. For example, one could shift his body clock from morning to evening by using the following schedule:

After the third day, one could be receiving bright light at the desired wake time, and not have to take any more melatonin.

Shifting from Night to Day Schedule

The schedule for shifting from night to day is the reverse of the previous schedule, but with one exception. It is important to avoid bright light before each light session.

Once the desired shift is achieved, light should be received at the regular, new wake-up time.

Cautions With Melatonin

In Australia melotonin is a controlled substance and only available by prescription from your doctor.

Since most of the effort in shifting circadian rhythms requires the suppression of melatonin, light is the most effective means of shifting rhythms. Therefore, melatonin should not be considered solely effective in shifting the body clock. It is also very important to avoid any bright light while melatonin is active in the system. Time-release melatonin also seems to be more effective than regular melatonin.

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Exposure to Bright Light and Darkness to Treat Physiologic Maladaptation to Night Work
The New England Journal of Medicine
Charles A. Czeisler, PhD, MD, Michael P. Johnson, AB, Jeanne F. Duffy
We conclude that maladaptation of the human circadian system to night work, with its associated decline in alertness, performance, and quality of daytime sleep, can be treated effectively with scheduled exposure to bright light at night and darkness during the day.

Short-Wavelength Sensitivity for the Direct Effects of Light on Alertness, Vigilance and the Waking Electroencephalogram in Humans: Steven W.Lockley Phd; Erin E.Evans,BS,RPSGT; Frank AJL Scheer,PhD; George C.Brainard,PhD; Charles A.Cziesler,PhD,MD; Daniel Aeschbach,Phd;