Human time production under constant routine

Previous reports have suggested that human time production of several seconds fluctuates across the day. In order to test whether human time production was controlled by the circadian process or by the homeostatic process, we investigate diurnal fluctuation of human time production under constant routine conditions. We found a common circadian feature in time production tests of 10 s by calculating Z-score for each subject; afternoon troughs and morning peaks. These results may suggest that human time production was modulated by the circadian process.