Adapting Test Timing to the Sleep-Wake Schedule: Effects on Diurnal Neurobehavioral Performance Changes in Young Evening and Older Morning Chronotypes

Abstract

The synchrony effect refers to the beneficial impact of temporal matching between the timing of cognitive task administration and preferred time-of-day for diurnal activity. Aging is often associated with an advance in sleep-wake timing and concomitant optimal performance levels in the morning. In contrast, young adults often perform better in the evening hours. So far, the synchrony effect has been tested at fixed clock times, neglecting the individual's sleep-wake schedule and thus introducing confounds, such as differences in accumulated sleep pressure or circadian phase, which may exacerbate synchrony effects. To probe this hypothesis, the authors tested older morning and young evening chronotypes with a psychomotor vigilance and a Stroop paradigm once at fixed morning and evening hours and once adapting testing time to their preferred sleep-wake schedule in a within-subject design. The authors observe a persistence of synchrony effects for overall median reaction times during a psychomotor vigilance task, even when testing time is adapted to the specific individual's sleep-wake schedule. However, data analysis also indicates that time-of-day modulations are weakened under those conditions for incongruent trials on Stroop performance and the slowest reaction times on the psychomotor vigilance task. The latter result suggests that the classically observed synchrony effect may be partially mediated by a series of parameters, such as differences in socio-professional timing constraints, the amount of accumulated sleep need, or circadian phase, all leading to differential arousal levels at testing. (Author correspondence: [email protected])

Keywords:

• Aging
• Cognitive interference
• Morningness-eveningness
• Sustained attention
• Synchrony effect
• Time-of-day

ACKNOWLEDGMENTS

C.S. was supported by the Lundbeck-Belgian College of Neuropharmacology and Biological Psychiatry and by the Belgian National Foundation of Scientific Research (FNRS). F.C. is supported by the FNRS. PP was formerly supported by the PAI/IAP Interuniversity Pole of Attraction P5/04. C.C. was supported by grants from the Swiss National Foundation. The authors thank A. Fadista for her help in data acquisition.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.