June 3, 1999 Writer: Cathy Keen
Source: Raymon McAdaragh, (352) 373-3387
GAINESVILLE, Fla. --- Graveyard shifts can be killers, but employees whose schedules include the wee hours actually stay alert and are more attentive on the day shift than other shift workers, a new University of Florida study finds.
Research on 37 air traffic controllers in Jacksonville found that those whose frequent shift changes included the after-midnight graveyard shift were better able to focus on the tasks at hand during the day, said Raymon McAdaragh, who did the study for his doctorate at UF in instruction and curriculum.
"What I learned is the opposite of what you would expect," McAdaragh said. "People on rapidly rotating schedules that include this graveyard shift have better attention allocation, quicker reaction times and are better able to learn cognitive tasks during the day shift."
Statistics show that about 20 percent of Americans in the labor force are employed in some kind of shift work, he said.
"I believe that the conclusions of Ray's study can be applied to industry, business, education and other fields that require people to work very late or very early hours," said Jeff Hurt, a UF professor in instruction and curriculum who supervised the research.
Studies have found that shift work knocks people's daily physiological and psychological rhythms out of whack, resulting in a kind of "shift work insomnia," much the way transcontinental flight causes jet lag, McAdaragh said. Sleepiness and fatigue accompanying shift work also is a safety hazard for many occupations, and experts say that people employed in shift work never adjust to it, even after several years, he said.
"Each year there are a number of controller errors, some of which lead to aircraft accidents," McAdaragh said. "Many of these may occur because controllers are affected by this misalignment of body rhythms."
In the UF study, 19 of the air traffic controllers worked two or three night shifts, from 4 p.m. to midnight, followed by two or three day shifts, from 8 a.m. to 4 p.m. The other 18 worked a rapid rotation of these two shifts, followed by a third one from midnight to 8 a.m.
Over seven days of computerized testing, the controllers working the rapidly rotating three-shift schedule demonstrated a quicker reaction time during a series of spatial visualization and tracking tasks on the computer, McAdaragh said. They also improved their attention skills when learning a new cognitive task, while the other group did not, he said.
"It's important that there is a significant difference between the two groups because attention allocation is a primary concern to the tasks involved in radar control," he said. "These tasks require a high degree of concentration on changing traffic situations, with a constant need to solve current and potential traffic conflicts."
Workers' attention also may be adversely affected during day-shift training sessions, he said.
Air traffic controllers tend to prefer these counterclockwise rapidly rotating work schedules over weekly rotating schedules anyway because of the greater breaks they provide between work weeks, he said.
Another reason controllers generally don't work steady nonrotating schedules is that the Federal Aviation Administration discourages the practice, McAdaragh said. Traffic generally is light on the night shift, and FAA officials feel controllers' proficiency in handling heavier traffic loads would deteriorate, he said.
One possible explanation for the poorer performance of people on the two-shift rotating work schedules in the study is that they may vary their sleep schedule more erratically or they become "evening types" with a loss of alertness during the day, McAdaragh said. After working two or three consecutive evening shifts, they may get used to staying up after midnight, continuing to do so even after switching to day shifts, he said.
More research on the subject is needed, McAdaragh believes.
"Since a large percentage of industrial employees work shift work, factors such as efficiency, safety and profit need to be understood in relation to the chronopsychological effects," he said. "By doing so, training and other types of programs could be introduced in the workplace to help employees."
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