Previous studies found that repeated incidence of circadian misalignment – the condition that occurs when individuals’ sleep/wake patterns are out of sync with their biological clocks – is not healthy. Circadian misalignment has been associated with increased risk of developing cardiovascular, metabolic and gastrointestinal disorders, some types of cancer and several mental disorders.
The way that nursing shifts have been scheduled since the nurse shortages of the 1980s makes nurses particularly susceptible to this problem. Hospital nurses who work with inpatients do so almost exclusively in 12-hour shifts. The day shift normally runs from 7 a.m. to 7 p.m. and the night shift covers 7 p.m. to 7 a.m.
Researchers studied questionnaires from 388 nurses who work at the Vanderbilt University Medical Center. The night shift nurses at Vanderbilt typically work a schedule that includes 3 days on night shift followed by 2-5 days off, when most switch back to a normal sleep cycle. That means most of them are shifting sleep cycles as frequently as twice a week.
“I was very surprised to find that nurses’ second most frequent strategy was the ‘no sleep’ strategy that often involved staying awake for the 12 hours before starting the night shift,” said Karen Gamble, an assistant professor of psychiatry and behavioral neurobiology at the University of Alabama at Birmingham, who worked on the study as a post-doctoral fellow at Vanderbilt. “That means they are skipping sleep for at least 24 hours straight.”
The researchers identified five distinct strategies that the nurses used to adjust their circadian clocks. The most common approach, used by about half the participants, was to sleep in late on the morning before their first night shift. A small percentage maintained a nighttime schedule on their days off. The other two strategies were intermediates.
While the study’s scope did not include determining the effect sleep strategies have on nurses’ performance, several questions assessed nurses’ adaptation, including: How well-adapted they felt; how long it takes them to get out of bed; how much caffeine they use; and how likely they are to fall asleep during the day. The responses indicated that the nurses who use the sleep deprivation strategy are the most poorly adapted of the five groups.
“Most people don’t want to work at night and those that do use what works best for them and their lifestyle,” observed co-investigator Nancy Wells, director of nursing research at Vanderbilt.
Scheduling is a very touchy issue and many nurses, particularly the younger ones, like the current system because it allows them to string together a number of days off without taking vacation, Wells added.
The researchers recommend that nurses should be advised to avoid the “no sleep” strategy when working nights and suggest that hospitals re-evaluate the way that they schedule nurses to reduce the frequency with which nurses switch sleep schedules.
The study results appear in Public Library of Science One.