An assessment of the relevance of laboratory and motorcycling tests for investigating time of day and sleep deprivation influences on motorcycling performance.

The aim of this study was to assess time of day and sleep deprivation impacts on motorcycling performance taking into consideration key variables, such as reaction time, motor coordination and vigilance that are principally involved in a riding task. Eight subjects participated in different tests sessions planned at 06:00 and 18:00h after a normal night's sleep and after a night of total sleep deprivation. During each session all subjects completed "laboratory" and "motorcycling" tests that were designed to assess each of the variables tested. As classically observed in sport performance, motorcycling performance demonstrates a time of day fluctuation by increasing from 06:00 to 18:00h during the day after a normal night's sleep. For each variable tested, the effects of sleep deprivation depend on the design of the test conditions. Thus, the data collected in laboratory specific conditions are more affected than those noted in arranged motorcycling situations. Taking into account that the sample size used in this study was limited, which may limit the results interpretations, these discrepancies suggest that during complex tasks, compensation mechanisms may be set up between different resources so as to maintain a good level of performance.