NEW YORK-
People who often return to work with less than 11 hours between shifts are at higher risk of sleep problems and severe fatigue than others, according to a new study.
Shift work disorder, a combination of difficulty sleeping and excessive sleepiness while awake, is known to affect night workers, but there’s been little research on people who rest less than 12 hours before returning to work for another shift at any time of day, researchers say.
“For now, all we know is that quick returns represents a possible work related health risk, and that getting enough hours between work shifts should be an aim when scheduling work hours,” said the lead author of the new study, Dr. Elisabeth Flo of the University of Bergen in Norway.
If quick returns impede sleep time and lead to sleep deprivation, they may be linked to the health issues typically associated with shift work, like increased accident risk, sleep disorders, cancer, metabolic disturbances, peptic ulcer disease and coronary heart disease, she told a foreign news agency by email.
People who are excessively sleepy because they have a work schedule that keeps them awake when they would normally be asleep, and have been in that state for at least one month, have shift work disorder, Flo said.
In both 2009 and 2010, the researchers mailed work and health questionnaires to a group of several thousand randomly selected nurses in Norway and 1,224 of them filled out and returned the surveys for both years.
Almost all of the nurses were female and they averaged around 34 years of age.
The nurses reported how often over the past year they had worked two shifts with less than 11 hours in between, usually entailing an evening shift followed by a morning shift with a break of only nine to 10 hours.
The surveys also included questions about mental and physical fatigue, anxiety, depression and hypothetical situations in which they might doze off.
On average, the nurses reported having 33 instances of “quick returns” between shifts over the previous year.
Nurses who reported more quick returns in 2009 were slightly more likely than others to qualify for shift work disorder or to have pathological fatigue, meaning they gave at least four of 11 questions on a mental and physical tiredness survey a “strongly positive” response.
Nurses who reduced their number of quick returns between 2009 and 2010 reduced their risk of pathological fatigue by about 30 percent.
Quick returns were not associated with excessive sleepiness, anxiety or depression between year one and year two, according to the results published in Occupational and Environmental Medicine.
“Workers and their managers need to recognize that workers on quick returns will likely need to attend to other activities besides sleep during their time off between work shifts, such as commuting round trip between work and their bedroom, getting prepared for sleep, and on awakening getting dressed and eating before going to work,” said Claire Caruso, a research health scientist for the Centers for Disease Control and Prevention National Institute for Occupational Safety and Health.
“Therefore, for example, eight hours between shifts will not allow eight hours for sleep,” Caruso, who was not involved in the Norwegian study, told the news agency.
“It should be a minimum goal that nurses should have enough time both to commute home and to have a full sleep period before the next shift starts,” Flo said. “In addition it seems advisable that quick returns should be avoided as far as possible.”
It’s not far-fetched to think that quick returns could be an issue in other shift-based professions as well, she said. The leeway to change schedules for more adequate rest time varies by position and by country, and some nurses may actually choose more consecutive shifts if it means more continuous time off to spend with family later, she said.
Recovery time is essential for everybody, but it is “human” to think that long free day periods are better than having enough free time between consecutive shifts, said Tarja Hakola, senior specialist at the Finnish Institute of Occupational Health, who was not part of the new study.
“There is no global way to avoid quick returns and every work place has to make their own practices,” Hakola said.
