Inside Logistics

New insight into working hours

"Morningness", "eveningness" and the problem of shift work has implications for DC workers


May 15, 2015
by MM&D Staff

Shift work is common in many industries, including health care, security, transportation and warehousing. Such sectors need employees to maintain high levels of attention in order to minimize risk.

But working shifts is known to lead to cognitive and behavioural problems through disrupted circadian rhythms and sleep patterns. In a new study published in Biological Rhythm & Research, authors Fatma Feray Selvi, Sibel Asi Karakaş, Murat Boysan and Yavuz Selvi find that shift work affects attention deficit, hyperactivity, and impulsivity among nurses, and that an individual’s chronotype—their natural tendency to ‘morningness’ or ‘eveningness’—is a relevant factor. They suggest that a person’s chronotype could help to evaluate their suitability for shift work.

It has been known for some time that shift-work schedules have a marked effect on circadian rhythms and the sleep–wakefulness cycle, leading to cognitive and behavioural problems.

In this study, Selvi, Karakaş, Boysan and Selvi surveyed 206 hospital nurses, 79 working on day shifts and 127 on night shifts. They used a number of tools and surveys to measure the nurses’ motor impulsiveness, non-planning, and attentional impulsiveness as well as how frequently the individuals experienced symptoms of inattentiveness and hyperactivity/impulsiveness.

The authors also identified the nurses’ circadian preferences using the Morningness–Eveningness Questionnaire (MEQ). This measure classifies individuals as morning-types, intermediate-types or evening-types, according to their reported times of activity and alertness.

Among the findings of the study are that shift workers have more attention deficit and impulsivity than daytime workers. Looking at the nurses’ chronotypes, Selvie et al. find that evening-type workers score significantly higher than morning-type employees for attention deficit. Morning-type workers report lower hyperactivity scores than evening- and intermediate-type workers.

The researchers also analysed impulsivity scores in relation to the nurses’ demographic characteristics—age, gender, marital status, working schedule, time in employment, tobacco use and duration of smoking—as well as to MEQ. This reveals that unmarried participants and shift-workers have significantly higher impulsivity scores. The average impulsivity score of evening-type workers is higher than those of both the other chronotypes.

“The most important outcome of this study was that those working on the shift system had more attention deficit and more impulsivity than the daytime workers. Even though the effects of shift work on cognitive functions have been analyzed before, this is the first study that has investigated the relationship between the work schedule and attention deficit, hyperactivity, and impulsivity,” the authors said.

The additional findings regarding workers’ chronotypes will be of practical use to employers: assessing whether individuals are morning-types or evening-types will help to determine their suitability for shift work.

Having alert and attentive workers is extremely important for fulfillment centres, both for pick accuracy and safety, especially around mobile equipment like forklifts and pickers.