Chronic short sleepers display slower reaction time, compared to adequate sleepers, but maintain an intact StartReact effect


Sleep curtailment impairs cognitive functions. Studies investigating the effect of sleep on simple reaction time (RT) tasks have been limited to acute sleep deprivation/restriction and none of these studies have tried to investigate the mechanisms behind this effect. Using a startling acoustic stimulus (SAS) during a simple RT task has been shown to involuntarily trigger a prepared movement through a faster pathway, termed the StartReact effect. The purpose of this study was to investigate the association between chronic sleep duration and movement preparation, during a simple RT task. Participants included 25 short sleepers (?6h) and 25 adequate sleepers (>7.5h), who performed a simple RT task involving a 20° ballistic wrist extension in response to either a control-tone (80dB) or a SAS (120dB). Testing included 6 blocks of 30 trials, the first 2 blocks were control blocks, and the last 4 blocks were considered experimental blocks where a SAS sometimes replaced the control tone. Results showed a significant sleep duration by type of Go-signal interaction on RT (F(1, 22)=5.22, p=.03), indicating that short sleepers had significantly slower RT than the adequate sleepers for the control tone but no significant RT differences were observed between groups for the SAS trials. These findings suggest that in addition to acute sleep deprivation, chronic short sleep is also associated with slower RT during voluntary movement execution. However, since sleep duration was not associated with the StartReact Effect, it indicates that the level of preparation is not the cause of these slower RTs.

Acknowledgments: Supported by NSERC and the Ontario Ministry of Research and Innovation and Science