The vigilance decrement in executive function is attenuated when individual chronotypes perform at their optimal time of day

Abstract

Time of day modulates our cognitive functions, especially those related to executive control, such as the ability to inhibit inappropriate responses. However, the impact of individual differences in time of day preferences (i.e. morning vs. evening chronotype) had not been considered by most studies. It was also unclear whether the vigilance decrement (impaired performance with time on task) depends on both time of day and chronotype. In this study, morning-type and evening-type participants performed a task measuring vigilance and response inhibition (the Sustained Attention to Response Task, SART) in morning and evening sessions. The results showed that the vigilance decrement in inhibitory performance was accentuated at non-optimal as compared to optimal times of day. In the morning-type group, inhibition performance decreased linearly with time on task only in the evening session, whereas in the morning session it remained more accurate and stable over time. In contrast, inhibition performance in the evening-type group showed a linear vigilance decrement in the morning session, whereas in the evening session the vigilance decrement was attenuated, following a quadratic trend. Our findings imply that the negative effects of time on task in executive control can be prevented by scheduling cognitive tasks at the optimal time of day according to specific circadian profiles of individuals. Therefore, time of day and chronotype influences should be considered in research and clinical studies as well as real-word situations demanding executive control for response inhibition.

Figure 1. Sequence of events for both strategy conditions in the modified SART.

The precision strategy condition, on the left, emphasised accurate response inhibition over fast responding. Digits turned red when the average correct response rate in no-go trials was below 0.71. The speed strategy condition, on the right, emphasised fast over correctly inhibited responses. Digits were presented in yellow when the average RT was above 440 ms and accuracy rate in no-go trials was not below 0.45.

Figure 2. Mean reaction times on the PVT for both chronotypes depending on time of day.

Each chronotype responded fastest at their optimal time of day and slowest at their non-optimal testing time. Vertical bars denote +/− standard error of the mean.

Figure 3. Accurate responses as a function of chronotype, testing time and block for the precision strategy condition.

Each chronotype showed marked performance decrements at the non-optimal testing time. Vertical bars denote +/− standard error of the mean.

Figure 4. Correlation between RT in the PVT and accuracy on SART for the precision strategy condition.