CircaTime: Effects of Circadian Rhythms on Time Perception During a 36-Hour Constant Routine in Healthy Adults

What this Trial Is About

Researchers are studying how the body's internal clock, known as circadian rhythms, affects how healthy adults perceive time, think, and feel during extended wakefulness. The study focuses on understanding changes in time perception, alertness, and mood over a 36-hour period without sleep. By controlling environmental factors such as light, posture, food intake, and activity, the study aims to isolate the body's internal clock and sleepiness effects on cognition and perception. This research may help improve shift work scheduling and activities requiring sustained wakefulness. Participants undergo a 36-hour constant routine protocol in a controlled sleep laboratory where they remain awake continuously. During this time, light levels, temperature, noise, posture, and physical activity are kept stable, and participants receive small, isocaloric snacks at regular intervals. Every two hours, they complete a series of tests measuring sleepiness, mood, reaction time, time perception tasks, decision-making, and color judgments. Saliva samples are taken regularly to measure melatonin levels, which indicate circadian phase. Throughout the study, participants are monitored for vital signs and any adverse events. Assessments include subjective sleepiness and mood ratings, psychomotor vigilance tests, and tasks related to time perception and cognition repeated every two hours. The primary outcome measures time-interval production error across the 36 hours. Secondary outcomes include reaction time, subjective passage-of-time ratings, and melatonin onset timing. After completion, participants receive recovery sleep arrangements. The study lasts about 36 hours in the lab, with prior screening and follow-up procedures.

Circadian Rhythms and Time Perception in Healthy Adults During Constant Wakefulness