How to Design the Optimal Schedule for Working Shifts

Working long shifts is nothing new to emergency medicine residents. In fact all emergency physicians feel the stress of shifts at some point, no matter how long they have been practicing. The bad news is, it doesn't get any better just because you have been doing it longer. But the good news is, there is something you can do about it.

Residents are in a unique situation because they have little control over their shifts. But by taking advantage of the opportunities you do have, you will be able to make your biological clock run a little smoother. Night shifts may be inevitable, but you can still maintain peak performance while working nights and ease both the stress of a night schedule and the adjustment from day to night shifts and back again.

Alertness and Performance

The main problem, of course, is that changing shifts means changing sleeping and eating patterns that upset the body's circadian rhythms. Alertness, speed, accuracy and reaction time are related to body temperature. People do best when their temperature is highest - usually in the middle of the waking period.

It's well established that performance for a wide range of tasks varies with the time of day. Most performance curves can be brought into line with 24-hour temperature curves. The higher the memory component of a task, the earlier in the day performance on such a task peaks.

"Memory is sharpest after restorative sleep. Morning people who like to go to bed and get up early have their temperature peak usually before noon. Evening types who like to get things done at night and then sleep in, have their temperature peak later, in the second half of the day," says Dennis Whitehead, MD, a former Speaker of the ACEP Council and currently medical director of emergency services and EMS Project medical director for the Dickinson County Healthcare System in Iron Mountain, Mich.

Body temperature drops during sleep. Adjusting the body's circadian rhythms, and thereby the temperature cycle, may take as long as a week. So, inappropriate phasing, trying to stay awake or to sleep when the circadian clock says otherwise, is a problem - especially with isolated night shifts, Whitehead says.

Single Night Shift Rotations

Some emergency physicians have advocated a single night shift system, wherein each physician works a solitary night shift attached to "normal scheduling." It's difficult logistically for small groups to use this schedule exclusively, but it is a viable option for large groups.

The issue of circadian fatigue during those single night shifts can be problematic, but some adjustments to sleep schedules have been proven to be helpful, notes Whitehead.

"After working an isolated night shift, go to sleep as soon as possible after work and force yourself to get up after four hours. This way you'll be sleepy at your normal bedtime and will be better able to sleep all night," he says.

Sleeping longer than four hours after working will significantly retard the next night's sleep, likely causing REM deprivation if one needs to be up early for a day shift the next morning.

For those working short stretches of night shifts, so called "split sleep periods" may be an effective strategy. Sleep in two four-hour periods adjacent to your normal sleep time. If you normally sleep from 2300 to 0700 and your night shift falls during that time, sleep for four hours immediately before and after work. Because the short rotation schedule doesn't allow for an effective shift of the sleep-wake cycle, the goal is to prevent body rhythms from shifting and still be able to stay awake and alert during the night.

Clockwise Monthly Rotations

Chronobiologists recommend clockwise shift rotation, with at least a one-month period when on long rotations to permit circadian stabilization. The body's innate circadian rhythm is a little over 25 hours, making it easier to delay bed time than to advance it.

The practice of weekly shift rotation is universally condemned in the literature because it takes at least a week for the body to adjust to the new shift, Whitehead explains.

"And, while 12-hour shifts are common, an eight-hour shift makes the adjustment easier. It takes longer to reset the biological clock across a 12-hour change than it does for an eight-hour adjustment," he says.

Exclusive Shifts

Historically, the circadian "gold standard" for any industry requiring continuous coverage has been to work the same shift all the time. The problem for residents is that rotating shifts make this almost impossible.

With long night shift rotations, the strategy of anchor sleep may minimize circadian desynchronization. Anchor sleep is a period of at least four hours during which one sleeps every day while on a particular shift rotation. For example, if you sleep from 0800 to 1600 after working nights and from 0400 to 1200 on days off, the overlapping interval from 0800 to 1200 constitutes anchor sleep.

"Sleeping until noon is preferable to sleeping all day for most people with families or other daytime commitments. By sleeping through at least half of the time normally reserved for sleep, circadian rhythms are 'anchored' to a particular schedule and minimally disrupted," Whitehead says.

The Thomas Schedule

Whitehead, along with Harold Thomas Jr., MD, and Debra Slapper, MD, have proposed a system called the Thomas Schedule that combines longer night shift rotations with isolated night shifts.

In this scenario, one physician works a month or longer on nights, while another works isolated night shifts to cover for that physician's nights off. Logistically, the Thomas schedule works less well with 12-hour shifts precisely because there are more nights off for the physician on long night rotation.

The person on nights for the month should not have more than two nights off in a row, otherwise they risk readjustment to diurnal rhythms. And it's important to schedule administrative meetings early in the morning or late in the afternoon to accommodate those working nights for a month or longer.

Working shifts is one of the many challenges of an emergency medicine career. But with some careful planning, you will still be able to get a good night's sleep.

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