Who would have thought that when Thomas Edison invented the lightbulb about 1880, that it would change the very nature of the workplace. Although there had always been a need in many industries to work around the clock, night and insufficient lighting made that nearly impossible. Slightly more than a century later, Edison's invention has been both a blessing and a curse. While it has facilitated entertainment, productivity, and emergency service operations, it has also enabled people to work throughout the night and the development of the nightshift. It is estimated that currently, 26% of American workers have some form of nonstandard shift schedule (Jaffe, Smolensky & Wun, 1996; White & Keith, 1990).
Over the past 100 years we have cut our nightly sleep by more than 20%, and in the last 20 years we have added about 158 hours (nearly a full month) to our commuting and annual work schedules. It is estimated that 90% of industrial and transportation accidents are due to direct or human error, with insufficient sleep as a major factor. Between four and six a.m. the rate of fatigue related accidents for single trucks is 10 times that of the day, when there is more traffic; other job errors also peak around that time (Scott, 1994). Some of the major disasters of our time have been related to shift fatigue: the Exxon Valdez, Chernobyl, Challenger disaster, Three-Mile Island, and Bhopal. Across all industries reduced job alertness costs an estimated $70 billion a year (Mapes, 1990). As early as 1978, concerns over the effects of shiftwork led the National Institute of Occupational Safety and Health to issue a warning that shift work and rotating shifts posed a significant health risk to workers (Colligan, et al., 1978).
Although relatively little research has been conducted with police officers, there is a considerable body of information that has emerged on shiftwork. Emergency services that involve continuous operations are particularly vulnerable to shift related fatigue. Compared with only 4% of day workers, 83% of nightshift workers report feeling tired and worker capacity typically declines between 5-10 % (Bonnet, 1990). Unsuccessful attempts to cope with this stress results in higher rates of alcohol and drug use, higher medical and emotional problems, and a higher divorce rate (McBride & Westfall, 1992). During shiftwork periods in law enforcement there are reports of increased errors (such as evidence mishandling), accidents, brutality, and illness and disability (Horstman, 1978). Many officers believe that their careers have become "capped" within the first 2-3 years because they are out of touch with the rest of the department and daytime community. As high as 80% of shiftworkers experience personal, social, and medical problems related to shiftwork (Caplan, 1988). In one study of 203 retired police officers were asked to reminisce about how they felt when they were shiftworking. In retrospect, the officers reported that the effects of shiftwork were actually worse than they had realized at the time (Spelten, Barton, & Folkard, 1993).
The effects of shift adjustment
Adjustment to shiftwork is based on the circadian rhythm (meaning "about a day"). This 24-hour cycle of alertness and rest is regulated by a biological clock in the brain. As light enters the eyes, a tiny mass of nervous tissue is stimulated and its action suppresses the pineal gland that produces melatonin--a substance that causes the body to prepare for rest and is present at about ten times higher amount at night than during the day. When there is little light, melatonin is produced which starts a cascade of chemicals that affect blood, glands, digestion, brain waves, body temperature, and our general alertness and level of arousal. It can be extremely difficult to fight this physiological switch that induces rest and sleep (Monk, 1990).
When a person attempts to resist the physiological need for rest the body can make its needs known even more clearly with signs of shift intolerance. An estimated 5-10% of the general population cannot tolerate nightshift due to the intensity of intolerance symptoms. These problems can include headaches, persistent fatigue, gastrointestinal problems (diarrhea, constipation, upset stomach, appetite loss), muscular aches and restlessness, and slowed reaction time.
More serious but latent medical problems can also emerge that have never been a significant problem before. Excessive strain due to insufficient sleep can exacerbate high blood pressure, epilepsy, diabetes, heart problems, intestinal disorders, insomnia, and depression. Some people are also more sensitive to medication that is taken to control such disorders as diabetes, seizures, blood pressure and heart conditions. The symptoms are so troublesome for some people that their physicians even recommend that they find new jobs that have more traditional work hours (Frese & Okandek, 1984). From 20-30% of workers in general are forced to leave the field in the first 2-3 years due to chronic medical problems (Harma, 1993).
Sleep disorders can also occur, making it difficult during off duty to go to sleep, stay asleep, or experience a high quality of sleep. About 63% of nightworkers complain of sleep disturbance. Sleep length of night workers may be only 4-6 hours compared to day and afternoon workers who average 7-9 hours. This loss of sleep can become a "sleep debt" that robs an officer of energy and alertness. Evidence of sleep deficit can be seen in as short a time as 2 days of inadequate sleep, and with as few hours of sleep loss. Significant sleep deficit can accumulate after more than 3-4 nights worked in a row, and some researchers believe that a schedule of 6 nights in a row may be too exhausting (Scott, 1994). When this occurs, an officer can experience brief periods of "microsleep" in which normal activities are engaged in, but the person slips into light sleep for periods of 1-10 seconds. In one study of microsleep, participants were asked to press a button when a bright strobe light was flashed directly in their eyes every few seconds. During microsleep they did not notice the light or even that they had been asleep (Dement, 1974). Microsleep does not give a warning.
The psychological and behavioral effects of shiftwork can be equally troubling. When keeping a vigil, as in surveillance work, as early as 20-35 minutes after starting, concentration and attention can begin to lag (Krueger, 1989). Higher thinking skills are also affected. When fatigued, memory and recall are slower, logical and arithmetic reasoning have more errors, decision making is slower, and report writing and comprehension are not as good (Balkin & Badia, 1988). There is often a temptation to take shortcuts that can result in not following procedures, mishandling evidence, and safety violations.
Emotionally, officers who are fatigued experience more frustration, irritability, and aggression; there is a higher rate of brutality complaints during nightshift duty. Restlessness, nervousness and agitation can lead to impulsivity, carelessness, and impatience. These reactions in turn make the work less satisfying and can lower morale, eventually contributing to higher absenteeism and turnover.
Shift schedule design
The effects of shiftwork have fostered a great deal of research on shift schedule design, although the results across various occupations and industries are not completely in agreement. Many shiftwork schedules involve four to seven days on and two to four days off. In Europe and in many American police departments, a shorter shift of two to four nights is frequently used, resulting in little or no shift in the circadian rhythm. Changing from a longer duty period to this shorter one has found improvements such as two-fold decrease in day fatigue, 40% decrease in auto accidents, 29% decrease in alertness problems, and 5% increase in satisfaction (McBride & Westfall, 1992). Such rotations require very careful calendar scheduling both at work and home.
When officers are on longer rotations it can be very challenging to adjust to shiftwork. As noted above, body temperature changes with circadian shift: temperature rises when more alert, and drops when preparing for rest. In some studies of longer rotations, even after 21 consecutive nights of work, the body temperature has not shown complete adjustment, suggesting that many workers may simply not adjust to nights. Even when permanent shifts occur and a worker is "entrained" or becomes conditioned to nightwork, as little as two days off and awake during the daytime can disrupt night adjustment and require the worker to become entrained all over again when going back on nightshift.
Complicating adjustment even more is the direction of shift cycles. Some organizations have structured shifts so that employees work earlier shifts each time they rotate duty. This has the result of not only upsetting the body clock, but makes the adjustment even harder by going against the direction of the circadian cycle rather than with it. It is generally accepted that shifts should move forward or clockwise (e.g., morning-evening-night), rather than counter-clockwise (Akerstedt, 1990; Barton & Folard, 1993; Freden, et al., 1984).
Finally, age and gender appear to modify the effects of shiftwork stress. Shift intolerance increases for people over age 40, although by that time they may have seniority such that night shift or rotations are no longer a major problem and they have learned effective coping techniques (Oginska, Pokorski, & Oginski, 1993). There is also some evidence that shiftwork is harder on women. Women report a higher injury rate than do men, and also report more shift adjustment problems (Barnes, 1996; Novak, et al., 1990): less sleep, more interrupted sleep, and more intolerance symptoms. This does not necessarily reflect an inability by women to perform under shift conditions; it more likely reflects their double burden of working two jobs--law enforcement and family. Working wives report during off duty hours typically spending their time in shopping for the family, house keeping, and having primary responsibility for child care (Hertz & Charlton, 1989; Oginska et al., 1993).
Part of the problem is that our society does not operate on a night schedule, and officers who get involved in diurnal or day time activity during days off, will continue to have entraining problems. Adjustment may never truly occur unless one maintains nocturnal activities during days off, and fixed sleep schedules rarely exist. Adjustment may be somewhat easier in large metropolitan areas that have a larger segment of late night and all night businesses (e.g., restaurants, shopping, etc.), but can be very challenging in smaller communities.
Although there is no single work schedule that is optimal for all tasks (Krueger, 1989), many industries and emergency services have moved from three eight-hour shifts over several weeks, to two 12-hour shifts over about four days. Moving from 8-12 hours does not seem to significantly interfere with performance, and four days is about the limit of doing nightwork without making circadian changes (Folkand, 1992; Walker & Eisenberg, 1995; Williamson, Gower, & Clarke, 1994) . Studies examining such schedules have reported few ill effects and several improvements: increased productivity, higher morale, lessened fatigue, better time blocks for free time, improved family relations, reduced commuting, improved health, and more job satisfaction. Nonetheless, it is not possible at this time to recommend that all police departments convert to such a schedule. It is more advisable to design a schedule that fits the demands, risks, and personal needs of each organization.
Family impact and adjustment
The adjustment to shiftwork places many demands on the family of the officer. Family and social activities are out of phase with the diurnal world, and spouse and children may question whether the shiftworking family member provides sufficient companionship, intimacy, support, sharing and protection (Smith & Folkand, 1993). This is particularly demanding on single people who are dating, young marrieds, and couples with young children. In addition, shopping, recreation, and socializing with friends are difficult to arrange at convenient times because of resting. Many fatigued officers simply find it too difficult to do anything off duty other than eat and try to catch up on sleeping, and reserve other activities for days off. Leisure activities are restricted, there is less participation in voluntary organizations, and less need fulfillment is reported (Frost & Jamal, 1979).
Spouses often complain that their partners are not available when they are needed, and they must develop their own interests, pastimes, and lifestyles--sometimes in a direction that does not support a marriage. Fatigue and mood, sometimes complicated by stress and trauma, make the officer less pleasant to be around, and some spouses will not have friends over because of the tension. In a recent study (Smith & Folkard, 1993), spouses of shiftworkers reported higher conflict (73%), social life suffers (63%), poorer contact with children (54%). In addition, they noted increased concerns over staying home along (67%), keeping noise levels down (66%), and making meals at inconvenient times (55%). Conflicts over these matters can accumulate over time which can escalate in intensity into domestic abuse, or the couple stops talking being around each other--they just give up. Both spouses initially feel guilty over the resentment of work interfering in family life, then they feel resentment toward each other. In a study conducted by the Police Foundation, 30% of police officer divorces were found to be related to stress in the profession, mostly resulting from shiftwork (Baxter, 1978). Another study of 1495 industrial nightshift workers found that there was 50% more divorce among that group, compared with day workers (Tepas, 1985). Clearly, shiftwork places additional stresses on relationships and requires that officers and families become better prepared for dealing with these pressures.
Nonetheless, there are many families who not only survive shiftwork, but thrive and can become more cohesive because of it. The best preparation is to educate everyone on why shiftwork is necessary, the risks of inadequate adjustment, and what can be done to adjust and cope more effectively. Departments can provide orientation to families as well as the officers and support social networking among spouses. Families can receive guidance in using family meetings to discuss concerns, balance home and family care responsibilities, and to formulate a family schedule calendar. Finally, when more detailed information or serious problems emerge, consultation with the employee assistance program (EAP) can be arranged (Anderson, Swenson, & Clay, 1995; Tepes, 1993).
There are also relatively simple and inexpensive mechanical arrangements that can be used to "shift-proof" the home. Domestic machinery (washer, drier, mower, etc.,) can be run during waking hours. The bedroom can be relocated to an area of the house where there is less traffic, higher insulation, and less noise. Double-glazed or sound resistant windows, wall to wall heavy rugs, and heavily textured curtains can also decrease noise. During sleeping hours the doorbell can be switched off, phone can be forwarded except for emergency calls, or answering machine used. No visitor/solicitor signs and scheduled visits can help decrease unexpected intrusions. White-sound machines or tape recordings can be used to mask other sounds, and ear plugs can be worn, although some officers dislike not being able to hear. Opaque curtains or sleep mask can be used to block out the light.
Some behavioral preparations can also help to shiftproof the home. Discussions with children about the importance of sleep time, and relating it to how they feel when they have to awaken early for a trip can increase their appreciation of rest time. People often find that developing a sleep routine, such as drinking warm milk, reading, or bath, can prepare one for rest. The practice of muscle relaxation exercises, meditation, and self hypnosis can build skills that not only help sleep but can aid anxiety control on the job (Anderson, Swenson, & Clay, 1995). Avoiding the stimulation of caffeine, large meals, alcohol, and excessive exercise before bedtime can also facilitate sleep (Dekker, et al., 1993). Finally, the bedroom should be associated only with sleep and intimacy--it should not be used as a workroom or TV room.
Preparing for shiftwork
Some efforts have been made to discover whether certain personality types are a better fit for shiftwork or night work. There has been strong interest in developing an inventory that can identify morningness ("day larks") and eveningness ("night owls") (Greenwood, 1991, 1995; Rohner & Schurig, 1990; Smith, Reilly, & Midkiff, 1989). Although it appears possible to categorize people who have a preference for and are more energized during the day, the eveningness style and its relationship to shift tolerance is more elusive. Other studies indicates that adaptation to shiftwork may be easier for extroverted, relaxed, stable, and flexible people than for introverted, anxious, reactive, and rigid workers (Iskra-Golec, 1993). Commitment to shiftwork, preference for night hours, optimism, and a feeling of control or mastery over worklife are also positively related to shift adaptiveness (Harma, 1993; Monk & Folkard, 1985). While it would be ideal to match officers' personality with shift schedule, this is difficult for the nearly two-thirds of workers who prefer exclusive day schedules and face a rotating schedule. Probably the best that can be done is to match people whenever possible and assist the rest in developing effective coping behaviors.
Nutritional recommendations are notorious for changing fads from year to year, but there is some consensus about what interferes with and helps shift adjustment. The brain uses a substance called tyrosine to make nerve transmitters for alertness, quick thinking, fast reaction, and memory. It uses tryptophan to make transmitters to make us slow down, feel sleepy, and reduce desire for control. It might be considered a horse race as to which one first gets to the brain to set the level of attention. Based on this idea, it is generally better to eat proteins first before taking a bite of carbohydrate in order to give the tyrosine a race advantage.
Officers on nightshift also often have the poorest food available and eat at irregular times. The lowest reported health ratings for workers were for those who changed the number and times of meals taken on each shift (Duchon & Keran, 1990). While some people cannot tolerate food after 1-2 a.m. and have digestive problems, officers should try to maintain three balanced meals a day even on night shift. The first one should be the largest and the one before bedtime the smallest. In addition, one should eat legumes and low fat dairy products, broiled or boiled rather than fried foods, and eat raw vegetables, fruits and other healthy snacks.
Taking alcohol and sleep aids to promote sleep are risky because of dependency problems, and they can become part of an upper-downer cycle when caffeine and stimulants are used in the morning to increase alertness. Such self medications are often problematic because of their ease of access and use, rapid onset, and potentially serious withdrawal effects. Coffee is most often used to enhance alertness, but can also be used to excess. One seven-ounce cup has between 65-175 mg. of caffeine in it, depending on how it is prepared. Although 2-4 cups probably provides optimal stimulation, some people have reported as high as 22 cups during on duty hours, with resulting irritability, anxiety, digestive problems, and insomnia. Additional complications of excessive caffeine intake includes longer sleep latency, increased negative mood (Dekker, et al., 1993). Other caffeinated substances include Jolt (100mg.), Mt. Dew and Mellow Yellow (54 mg.), tea (30-70 mg.), chocolate and cold relief tablets (30 mg.). Caffeinated substances probably should not be taken five hours before end of shift if the shift is followed by sleep time.
There is growing evidence that melatonin tablets (2-10 mg.) can be used to help reset the body clock, and they have been used to relieve the adjustment of jet lag, which is similar to shift fatigue. However, there may be some side effects (e.g., prolonged grogginess on waking) and there are no studies on its long term health effects (Brown, 1994). There are also some studies with benzodiazepine and amino acids with flight crews and military personnel, but these are purely experimental, for emergency situations, and both produce side effects (Krueger, 1989). There is also research interest in whether scents can facilitate certain mood states, such as the fragrance of lavander assisting sleep, or peppermint stimulating alertness, but results are inconclusive. At this time there are no "magic bullets" that are endorsed to relieve the effects of fatigue.
There is evidence that exposure to bright light can stimulate the brain to suppress melatonin and help reset the circadian rhythm (Eastman, 1990). Since bright daylight is 2500-300 lux intensity, exposure to bright light before and during night work can increase alertness. Working in northern climates where winters are dark and long, and work indoors may also deprive people from sufficient light, and some can develop subclinical cases of seasonal affective disorder (SAD) that increases symptoms of depression and fatigue. Bright lighting and decor and well lit break areas can help. Light goggles in patrol cars might also maintain alertness, but would also unfortunately interfere for several minutes with night vision. Workers who are exposed to arrays of bright, broad spectrum lights report that they feel better the night of the treatment, feel more energetic and less tired, and are able to adjust more quickly to shift changes (Stewart, Hayes, & Eastman, 1995). To prevent the equivalent of shiftwork low light exposure, dispatchers and other personnel who work inside during the day should take regular breaks to expose themselves to bright outside light. Likewise, officers getting off duty as the sun is coming up should wear dark glasses on their commute home to facilitate melatonin production in preparation for sleep.
During World War II, Generals Eisenhower and MacArthur had reputations among the troops of never sleeping because they would appear at all hours in the field. They actually had developed the skill of napping in which they would catch several minutes of sleep here and there, punctuated by their activity. Since as many as 70-80% of police officers admit falling asleep once a week on nightshift anyway, napping is currently being investigated as an option for shiftworkers (McBride & Westfall, 1992). Although results are inconclusive, it appears that naps of 10-40 minutes prior to night shift and before sleep debt occurs, or during quiet periods of duty, can improve mood, energy and alertness. Studies indicate that preventive naps can maintain acceptable levels of performance, while performance may decline up to 30% without naps in some circumstances (Bonnet, 1990). There are cautions however: sleeping too long can bring about sleep inertia (grogginess) that can take 5-10 minutes to recover from, and can interfere with later regular sleep. There can also be a "sympathy" affect on the awake patrol partner who is trying to stay alert while the other naps, and who can feel isolated without someone to talk with.
Finally, officers can raise attention and alertness level by maintaining stimulation in their immediate environment. Although music is usually discouraged, it can help alertness, as can conversation with a partner or dispatcher. Refreshing activities such as a brisk walk, cold air, water on the face, open window, and even singing can also provide brief stimulation. Many of these refreshers are only temporary, and even regular physical conditions, while improving mood and general well being, has not been found to increase overall shift adjustment (Bonnett, 1990; Krueger, 1989). The key is to prevent fatigue before it becomes sleep debt and becomes more difficult to reverse.
Shiftwork is a necessity in industrialized nations and particularly for continuous operations and emergency services. The impact of shiftwork on the body clock can produce adverse physiological, psychological, and behavioral problems that interfere with job performance and satisfaction. Family and social involvement can also suffer. Many of these effects can be prevented or reduced by an integrated effort on the part of the department and officer to develop countermeasures to shift fatigue. These include designing effective shift schedules, orientation and education for the officer and family, shiftproofing the home, promoting healthy diet and exercise, considering new research on light exposure and napping, and developing skills in sleep preparation and stress coping.
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