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14 The significance of the physiological changes associated complex undertaking and should be guided by a person with sleeping pills make it difficult to recommend use of most knowledgeable in circadian physiology. Additionally, the commercially available pharmaceutical products at this time. benefits of resetting the circadian rhythm can be maintained only through fairly rigid adherence to the procedure and ensuring that other time cues (e.g., daylight) are minimized Melatonin (McCallum et al., 2003). The idea is to use bright light exposure to shift circadian Melatonin is a natural sleep sedative hormone produced by rhythm toward work schedule requirements, so that the oper- the pineal gland in the brain. Melatonin levels increase in the ator will obtain more sleep and be more alert when on the job. blood stream during hours of darkness. Commercially avail- The required light is in the range of 3000 to 10000 lux-- able synthetic melatonin sold in health food stores is often much beyond that obtained simply from indoor lights. used in attempts to induce sleepiness and to help one adjust Special equipment is required to generate this level of illu- the circadian rhythm to new schedules (e.g., to overcome jet mination, and some evidence suggests that the green wave- lag after transmeridian travel). However, the production of length is especially effective. Using light exposure for several synthetic melatonin is not regulated by the Food and Drug hours over a several-day period is usually most effective in Administration, so the quality and purity of individual pack- shifting the circadian rhythm, although periods as short as ages of the product is inconsistent. 30 minutes have been shown to have an effect (Wright and If one can obtain good quality synthetic melatonin and a Lack, 2001). proper use regimen can be worked out, use of melatonin This countermeasure has been particularly useful for pilots offers good promise to assist drivers in stabilizing their and other transport workers who either rapidly shift through sleep schedules. Because melatonin naturally dissipates in multiple time zones or who work on a forward rotating sched- the blood stream in bright light, its use as a sleep sedative is ule that changes by one shift each rotation (e.g., day shift, effective only in a darkened room, or a blackened-out truck afternoon, night). Given that motorcoach operators do not sleeper berth. Many drivers report successfully using mela- quickly transit across multiple time zones, it is unlikely that tonin to induce sleep during their required down time when they will find this countermeasure to be very practical in their they ordinarily might not have gotten to sleep without it. work situation. The sleep inducing properties of synthetic melatonin are short term. Although potentially helping an individual fall asleep more quickly, the use of melatonin will not neces- COUNTERMEASURES THAT HAVE sarily lead to longer sleep periods. Those who successfully MINIMAL EFFECTS OR MAY CAUSE use melatonin as a sedative take it in a pill form in hopes it HEALTH PROBLEMS will help them fall asleep quickly at times when they might The following fatigue countermeasures are not supported otherwise have trouble sleeping (e.g., during daylight hours). sufficiently by scientific data demonstrating their effective- Individual experiences with commercially sold synthetic ness (e.g., diet or aromatherapy) or they may cause health melatonin vary widely, perhaps partly because the actual con- problems (use of tobacco and/or nicotine). tents of pill form melatonin are not clearly identified by the Other countermeasures that have been commonly reported, manufacturers and very likely because no recommended plan such as exercise, diet, or listening to the radio have minimal of use regimens have been succinctly worked out as of yet. or no lasting impact on driver fatigue, even though people Medical research continues in numerous government and think they do. The countermeasures included in this category university research laboratories to determine the potentially are as follows: promising use of synthetic melatonin as a sedative and to identify any as-yet-unknown side effects. If commercial drivers plan to use synthetic melatonin Nicotine (not an effective stimulant for maintaining over a period of time, it is recommended they consult with alertness); a physician to determine what the latest research findings Ventilation and temperature (effects are fleeting and are on repeated use (National Sleep Foundation, 1997). temporary); Exercise (taking rest breaks and exercising energizes one for a short while, but then onset of driver drowsiness Bright Light returns quickly); Diet (longer term solution to health, wellness, and fit- The use of bright light as an operational fatigue counter- ness helps to a point); measure refers to timing the exposure to outside or bright Sound (noise-induced alertness gets old and tends to be indoor light in order to shift the circadian rhythm to corre- aggravating to a tired driver); and spond to a new work schedule or to enhance alertness. Use Odor/Fragrance (fleeting effects are not very helpful in of light exposure for resetting the circadian rhythm is a maintaining alertness).