How Do Individual Differences in Circadian Rhythms Influence Time Perception? A Randomized Crossover Study of Circadian Alignment Effects on Time Judgment and Cognition in Healthy Adults

What this Trial Is About

Researchers are studying how a person's natural daily rhythm, known as their chronotype, influences how they experience and judge time. This study focuses on healthy Danish-speaking adults aged 23 to 45 who identify clearly as either morning-type or evening-type. The goal is to see if time judgments and alertness differ when tested at a person's preferred time of day compared to a non-preferred time. The study also looks at how decision-making and social responses may change with circadian timing. Participants take part in two lab sessions on the same day in a crossover design: one session at their preferred time (e.g., morning for morning-types) and one at the opposite time. During each session, they complete computerized tasks measuring time estimation and production, vigilance through a psychomotor vigilance task, decision-making, responses to social information, and simple color-vision tests. Some participants will wear a wrist actigraphy device for one week before testing to track sleep-wake patterns. Throughout the study, participants complete short questionnaires about sleepiness, mood, fatigue, and their perception of time before, during, and after testing. Testing occurs under standardized lab conditions with scheduled breaks. Researchers measure outcomes such as time estimation bias, vigilance lapses, and decision-making metrics. Participants receive compensation after completing both sessions, and their data are handled securely. The entire participation takes place on one day, with results to be published regardless of outcome.

Circadian Timing and Time Perception in Healthy Adults