How does one night of sleep deprivation affect the internal clock?

Twelve subjects performed two temporal tasks, one explicit (Experiment 1) and one implicit (Experiment 2) after one night of sleep deprivation and after one night of normal rest. Experiment 1 involved a 1100-ms duration production task, and in Experiment 2 subjects performed a word identification task requiring implicit estimation of vowel duration (around 150 ms). One night of sleep deprivation had the same pattern of effect on explicit timing in the suprasecond range and implicit timing in the millisecond range. Specifically, sleep deprivation induced productions of shorter intervals in the duration production task and estimation of segmental durations as being longer in the word identification task. Both results are consistent with an acceleration of pacemaker rate. Moreover, in both experiments, we found a correlation between the alertness level of participants and the size of the effect. Therefore, sleep deprivation, which physiologically manipulates cortical arousal level, produced similar performance modulation in suprasecond explicit and subsecond implicit tasks suggesting a common mechanism. (C) 2012 Elsevier Ltd. All rights reserved.