Memory Based Performance Measures in Studies of Shiftwork

Abstract

The phase of the circadian rhythm in performance efficiency on a given task is known to be influenced by the memory load involved. Two experiments were performed to determine whether memory load also influences the rate at which rhythms adapt to the phase-shifts involved in (a) transmeridian flight and (b) a long period of nightwork. In the first study, high and low memory load versions of a performance test were given to a 25 y old female subject experiencing a 5h eastward change in time-zone. Differences were found both in the initial phase of the two versions of the test and in the rate at which this phase adapted to the new time. In the second study, two young male subjects, working 21 consecutive night shifts, were given high and low memory load versions of the performance test, and a calculations test, every 4 h around the clock. The results were similar to those of the first study: a cosinor analysis revealed that despite periods of arhythmicity there were large differences between the rate of adap...