Shift work is commonplace in law enforcement.
Although there is a large amount of research that addresses shift work in other industries, police officers are often unaware of these studies. In a 1986 review of 200 studies done on shift workers, 63 percent complained of sleep disturbance compared with 20 percent of those working only day shift. Shift workers were also found to average only five-hours of sleep daily when on rotations lasting less than three weeks, compared with eight hours of sleep for day workers and those whose shift rotations last longer than three weeks. Longer shift rotations give the body more time to adjust.
Shift workers are eight times more likely to develop stomach ulcers than those who work only day shifts. Mood swings and depression are up to 15 times more likely in shift workers than in non-shift workers. In addition, alcohol abuse, high blood pressure, divorce, infertility in women and work-related accidents are all more common among shift workers.
There are basically two types of sleep, both of which are based on the presence or absence of rapid eye movement (REM). These movements can then be recorded and studied by means of an electroretinogram. Slow wave sleep (SWS) is characterized by cortical brain cells firing synchronously in slow wave spikes. Most sleep in this stage happens early in the sleep period. It is often difficult to arouse someone an hour after onset of sleep because slow wave sleep is the deepest. SWS is very important for physical recuperation, and those individuals deprived of it often complain of fatigue and muscle aches.
The second type of sleep is REM sleep. This is where the brain is active and the body is inactive. REM sleep typically occurs after about 90 to 120 minutes of non-REM sleep. Most sleep periods will have four to six REM episodes. REM sleep is vital for psychological wellbeing. Those individuals deprived of it typically complain of moodiness and irritability. Since REM sleep is clustered toward the end of the normal seven to eight-hour sleep period, those whose sleep tends to be shorter or fragmented, as in shift workers, are more likely to be REM-deprived.
The traditional shift rotation is a weekly counterclockwise rotation. Recently, it has begun to fall out of favor because medical research has demonstrated that it leaves the biological clock in shambles. Researchers now increasingly recommend clockwise shift rotation with at least a month between rotations to allow for circadian rhythm stabilization.
The Gold Standard circadian rhythm for any industry that requires continuous service has been to work the same shift all the time. Those working shifts exclusively must maintain the same sleep period, even during nights off, to prevent disruption of their biological clocks. Because sunlight is a powerful time-giver, nocturnal training will be lost after two or three days unless this rule is strictly followed. Most police officers resist this concept because it interferes with daytime social and family functions. Unfortunately, resistance also compromises anchor sleep, which minimizes circadian desynchronization.
Anchor sleep is a period of at least four hours during which one sleeps every day while on a particular shift rotation. If you sleep from 8 a.m. to 4 p.m. after working nights, for example, and from 4 a.m. to noon on days off, the overlapping interval from 8 a.m. to noon is called anchor sleep. Sleeping until noon is preferable to sleeping all day for most individuals with families and daytime social commitments. By sleeping through at least half of the time normally reserved for sleep, the circadian rhythms are anchored to a particular schedule and minimally disrupted.
Napping is thought by most investigators to be restorative and useful in promoting alertness during or following night work. Napping before work seems to provide some benefit, and most medical researchers believe it does no harm. If you do nap, allow at least 20 minutes before starting your shift to leave enough time for sleep inertia to dissipate. Power naps of 30 to 45 minutes can be helpful for maintaining alertness. However, napping for longer than one hour can affect the next night's sleep. A longer nap is useful prior to a night shift.
Exposure to bright light changes the pattern of a hormone called cortisol. This hormone affects the subjective assessment of alertness and improves the ability to think and process information. Shift workers exposed to a 10,000 lux ambient-light environment had significantly higher levels of alertness and better cognitive performance across an eight-hour shift than shift workers in a one to 20 lux ambient-light environment. It is beneficial to avoid bright light prior to daytime sleep and to spend one to two hours outside in bright sunlight after daytime sleep.