Comparison of controller attention decrease during different break patterns in night shifts.

Fricke-Ernst, C., Kluge, A., and Kötteritzsch, A. (2011). Proceedings of the 55th Annual Meeting of the Human Factors and Ergonomics Society (HFES); September 19-23, 2011, Las Vegas, Nevada, 1195–1199. Santa Monica: HFES.


Night shifts result in a high pressure on employees’ health. Regarding air traffic control, they may also represent a safety issue. Research showed that cognitive performance is decreased at night (Monk 1996) and safety risks increase starting from the second working hour without a break (Folkard et al. 2005). Investigating a request to extend the middle part of a night shift due to little traffic, different break patterns are compared in terms of avoiding health and safety issues. 189 air traffic controllers (ATCOs) from the Eurocontrol Maastricht Upper Area Control Centre in the Netherlands were tested during night shifts lasting for 7.5 hours. During the night shift, two teams, each consisting of two air traffic controllers, were working: While one team was on break, the other took over. They were assigned to three break patterns, with four or five hours of break or a split of the night shift. Each team was tested three times during normal operation. They estimated their subjective sleepiness using a subjective measure, the Stanford Sleepiness Scale, and filled in an objective measure, the d2, to measure attention. Furthermore, one measurement took place during a regular day shift in order to control the night shift data. Results show that five hours of working without a break does not have a negative impact on attention compared to the two other work-break patterns. External validity is given, since the study was conducted during normal operation. However, it was not possible to control and evaluate all confounding variables, as this would have disturbed the ongoing safe working processes of the scheduled shifts. Therefore, future research that examines individual differences in attention and considers the different activities during the breaks of the ATCOs still needs to be conducted in order to clearly identify an optimal break pattern for night shifts.