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Around 40% of people appear to be strong larks or owls, which can be both an advantage and a disadvantage, depending on the type of lifestyle they lead. For example, some owls have trouble in school, because they cannot wake up early enough for classes, and forcing themselves to wake up results in a disruption of their circadian rhythms, but they do very well on night shift jobs. Larks, on the other hand, do not cope well with late shifts at work, although they can get up for early classes without difficulty.

Studies of the various chronotypes have illustrated that they persist despite race, gender, socioeconomic background, education, and other factors. This suggests that the chronotype is in a sense hardwired. For people who are extremely rigid morning or evening people, this can represent a problem, as it is easy to disrupt their circadian rhythm. (Corboy emphasis)

Many larks, for example, struggle with social obligations which require them to stay up late, while people with a mid-range chronotype can adjust their schedules to accommodate a few late nights on occasion

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What is a Zeitgeber?

[www.wisegeek.com]

A zeitgeber is an external cue which influences the operations of the internal clock in an organism. The classical example of a zeitgeber is light, which leads some organisms to wake up, while others go to sleep. An interruption in such cues can confuse an organism, potentially causing health problems and functional difficulties, as demonstrated in numerous studies.

The term was coined in 1954 by Jürgen Aschoff, a German biologist who studied circadian rhythms. In German, “zeitgeber” means “time giver,” so in a sense, you could consider a zeitgeber to be like a natural alarm clock, triggering some sort of change in an organism's internal clock, like a cue to wake up, eat, or engage in various activities.

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Emergency Medicine Awakening to Sleep Deprivation Issue





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By Douglas Page, © 1998

Sleep is as important to emergency physicians as sutures and sterile gloves. High stress, aggravated by erratic shift scheduling and sleep deprivation, is the major cause of the high burnout rate among EPs. Some studies suggest the average longevity in the specialty to be as short as 10.5 years.

While other medical specialists, such as surgeons and obstetricians, are exposed to the vagaries of on-call night work, no other specialty routinely schedules night shifts. Working different shifts wreaks havoc with biological clocks, the cumulative effects of which amount to a condition known as sleep deprivation - an issue receiving more and more attention recently in emergency medicine residency curricula.

The reason for the concern: Evidence suggests EPs do not think as clearly or quickly toward the end of a night shift, especially at the end of a string of night shifts. "Research has shown sleep-deprived and post-call interns and residents make more mistakes, are less vigilant and have worsened mood (anger, frustration, hostility) than when they are not sleep-deprived," says Barbara Phillips, MD, University of Kentucky professor of medicine and director of the Sleep Apnea Center at Columbia Hospital, Lexington. "This is not the condition I want someone to be in who is taking care of me."

Attempting to switch to or from a nocturnal schedule, says Harold Thomas, MD, FACEP, of the American College of Emergency Physician's Well-Being Committee, is similar to an orchestra that starts with one conductor then switches in the middle of a performance to the beat of a different conductor, resulting in a cacophony as the instruments adjust at differing rates to the new maestro. "This jet-lagged feeling while the different rhythms adjust at different rates is the inevitable result of attempting to reset one's bodily clock to a nocturnal schedule - a condition known as circadian disharmony."

Sleep is divided into two types: rapid eye movement (REM) dream sleep, and non-REM sleep. The body cycles through both types repeatedly during sleep periods. Non-REM comes in four stages. Stage I is the initial 10 to 15 minutes of any sleep episode. Subjects awakened from Stage I will deny having slept at all. Stage II, accounting for 50 percent of sleep episodes, is the least understood and is the matrix from which all remaining stages proceed. "Sleep stages are typically studied by selectively depriving a subject of that particular stage and observing the results," say Thomas. "Attempts to selectively deprive a subject of stage II sleep, results in total sleep loss because it is impossible to enter other stages without going through stage II. Stage II is the stage least likely to be made up after a period of sleep deprivation, and the most likely to be increased with the use of sedatives."

Stages III and IV, collectively called slow wave sleep (SWS), account for 20 percent of the sleep period and are felt to be important to body repair. These are the stages during which growth hormone is secreted during normal sleep, says Thomas.

During REM sleep, which accounts for 20 to 25 percent of the sleep period, the brain becomes just as active as when awake, but all the muscles are turned off and the body loses its thermoregulatory properties. REM is thought to be important for psychological adjustment and development.

Some sleep facts. Caffeine causes a more rapid than normal cycling between stages. Alcohol suppresses REM sleep. Sedatives result in almost exclusively increasing only stage II sleep, which is not particularly restorative. Daytime sleep is typically 1.5 to 2 hours shorter than nocturnal sleep, with REM the most shortened. REM occurs every 90 minutes. SWS usually fades out after the first third of the sleep period.

The problems of rotating shifts generally stem from working in opposition to the body's normal circadian rhythms, resulting in a phenomenon known popularly as 'jet lag'. The sleep/wake cycle is one of the most important of the body's various rhythms. According to Thomas most circadian rhythms have both an endogenous component (regulated by an internal clock located in the supra-chiasmatic nucleus of the hypothalamus) and exogenous component. "The exogenous component is composed of various time clues, called zeitgebers," he says. "One of the most powerful zeitgebers is the light/dark cycle."

The EM establishment is responding to the issue of sleep deprivation. "Sleep deprivation is definitely a major issue," say Dennis Whitehead, MD, FACEP, chief of emergency medicine, Dickinson County Healthcare System, Iron Mountain, Mich, who lectures on the subject. "It's beginning to be addressed. It's certainly more of an issue with us than other specialties because we're the only ones that plan on having to work night shifts." Because there is no down time in the ED, emergency physicians must be functional at all times, even though statistics show 80 percent of shift workers develop chronic fatigue, sleep disturbances, peptic ulcer disease and gastritis at a rate four to five times that of the day-worker population. Whitehead estimates the risk of working rotating shifts approaches that of smoking one pack of cigarettes per day.

"We lecture our residents on the importance of sleep characteristics and strategies to improve their ability to function well at night," says Carl W. Gossett, MD, FACEP, assistant professor, department of emergency medicine, Texas A&M University. "There are longitudinal studies ongoing by several groups of EPs addressing the longevity, health and well-being of EPs, specifically focusing on our shift work patterns."

Recent findings, most of them disturbing, in the field of sleep and sleep deprivation have focused attention on the hospital culture that sees long working hours as part of the young doctors' initiation. Last fall, the Australian Medical Association launched a four year campaign targeting doctors' working conditions, following the death of a 26-year old physician who,it was believed, fell asleep driving home after working the previous day and night with only three hours sleep. No other occupation, the campaign points out, accepts 36 hour shifts. Even truck drivers and locomotive engineers are relieved after 8 hours on the job.

"There is solid, scientific evidence that it's extremely unhealthy to work nights," Whitehead says. "Anybody who has to work nights for any significant portion of their careers can expect about a 20 percent loss of life span." Cardiovascular mortality has been noted to be increased among shift workers, as has the divorce rate. Shift workers are also known to have higher rates of depression and substance abuse.

Moreover, there is the question of how sleep deprivation affects quality medical care. Bertrand M. Bell, MD, in a letter to the editor, "Journal of the American Medical Association", Vol. 274:6, August 9, 1995, writes, "The occurrence of errors among health officers is attributable to sleep deprivation, chronic fatigue and inadequate supervision. The culture of the medical practice experienced by residents and interns encourages them to hide what they do not know and makes extremes of sleep deprivation and chronic fatigue be accepted norms of behavior among physicians."

A Bradley University sleep deprivation study reported in the journal "Sleep" (Pilcher and Huffcutt, 1996) found on a scale of one to 100 for overall functioning, sleep-deprived people earn a nine, while the average well-rested person earned a 50. The researchers found that mood suffers the most after sleep loss, falling to below one on the scale. Cognitive abilities barely reach one, and motor skills registered less than half of the well-rested average. This perhaps explains why several recent major disasters (Exxon Valdes oil spill, Three Mile Island and Chernobyl nuclear incidents, Challenger explosion, Bophal chemical accident) have been attributed to human error; all occurred on the night shift, when alertness is at its lowest. A U.S. Army study confirmed that sleep deprivation degrades the higher, more complex mental processes yet leaves simple mental processes unaffected. The study found that soldiers in a sleep-deprived state, while still able to put the cross-hairs on a target and fire accurately, could no longer be depended upon to distinguish friend from foe - which may help explain friendly fire incidents.

What do experts recommend to minimize the effects of unavoidable shift work and subsequent sleep deprivation? From a circadian perspective, says Thomas, "the gold standard is never to rotate shifts. A group lucky enough to find someone willing to work permanent night shifts should work hard to retain them and compensate them appropriately. Without a permanent night worker the best rotation is to have group members work a long string of nights, four to six weeks. The idea is that each person can group their nights for the year together and only have to shift their circadian rhythms twice, once coming onto nights and once coming off."

This never-rotate recommendation differs from some ED practices. The policy at Long Island Jewish Medical Center, for instance, is to prevent residents from working more than three of four nights in a row.

"The major benefit of working many nights in a row," says Thomas, "is that once adjusted to nights one will be alert, well rested and be able to provide optimal patient care, rather than struggling to stay awake for every single night shift. With the use of bright lights, and possibly melatonin, rapidly adjusting circadian rhythms has become possible."

Gossett also says the best pattern is to work extended night shift periods, instead of interspersing one's regular day schedule with frequent night shifts. "If you have to work nights each month you should gradually shift your circadian rhythms in a clockwise fashion and then work an extended period of nights in a row with no more than two nights off," he says.

One pharmacological agent that holds promise for the shift worker concerned about circadian rhythms is melatonin, a hormone secreted nightly by the pineal gland in response to darkness. "Melatonin is a sedative," says Thomas, "but more importantly has been shown to hasten resetting of circadian rhythms. Several studies of jet lag have shown significant improvement with melatonin." One study, "Efficacy of Melatonin in Facilitating Emergency Physicians' Adjustment to and Recovery from Night Shifts", presented by Laurie Beth Gesell, MD, and Kent Hall, MD, at the annual SAEM meeting last May, found that melatonin helped EPs feel more awake and function better, but after discontinuation of melatonin, sleep was impaired and EPs felt more fatigued. Another study, "Effect of Melatonin on Circadian Rhythms Following Shift Work in Emergency Medicine", presented by Kenneth Rice, MD, at the same meeting, found no clinical benefit to melatonin in sleep efficiency or daytime job performance following a period of shift work.

There are other behaviors EPs can use besides ingesting stimulants or sedatives to minimize the effects of shift work. "Adjust your diet with complex carbohydrates at bedtime," says Gossett. "Avoid stimulants such as caffeine or alcohol. No sleeping pills or sedatives are appropriate. Have a bright-lighted work space when you arrive. Maintain regular exercise and social gatherings. Do not try to live a daytime existence while working night shifts. Always maintain good sleep hygiene with a darkened room and no disruptions. Maintain an anchor sleep period."

Lee Shockley, MD, FACEP, emergency medicine residency program director at the Denver Health Medical Center, had special sleep quarters built at his house. "I have a 'bat cave' in my basement," he says. "It's sound proof and light proof for sleeping during the day. It makes a huge difference to the quality of my sleep, plus it allows my family to still be active without fear of waking me up."

-end-

Article appeared in the March, 1998, issue of Emergency Medicine News.

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Stoic
'In passing, I heard someone mention there is speciality known as casino design or casino architecture.'

My info may be somewhat dated now but at one time there was a University set up in Vegas, funded by the big dogs, to study such subjects a 'casino architecture'--- which wasn't about the building of a mock Venice or mini Paris but was concerned with ways to manipulate the environment and the people in that environment to improve the bottom line. I doubt that such research has been discontinued.

Any effective findings would, in the manner of these things, not have remained exclusively in the hands of the big dogs. The big supermarket chains do similar research on their own environments and implement any findings to encourage the impulse to buy.