This study examines how the internal body clock (circadian rhythms) influences the way healthy adults experience time, think, and feel when they stay awake for an extended period. Participants will spend about 36 hours in a controlled sleep laboratory while remaining awake the entire time. Light, posture, food intake, and activity are kept as constant as possible (a "constant routine") so that changes over time mainly reflect the body's internal clock and increasing sleepiness, rather than changes in the environment. Every two hours, participants complete a brief test battery that includes ratings of sleepiness and mood, a reaction-time task, and short tasks that assess how fast or slow time seems to pass, how accurately they can estimate time intervals, how they respond to simple decisions, and how they judge colours. Saliva samples are collected repeatedly to measure melatonin, a hormone that indicates circadian phase. By comparing changes in behaviour, perception, and melatonin levels across the 36-hour wake period, the study aims to identify when during the circadian cycle people are most vulnerable to distortions in time perception and reduced alertness. The findings may help improve scheduling of shift work and other activities that require sustained wakefulness.
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Time-Interval Production Error Across 36-Hour Constant Routine
Timeframe: From the beginning of the constant-routine wakefulness session through 36 hours of continuous wakefulness (time-production task completed every 2 hours).