Effect of napping on response time, perceived sleepiness during the Ultra Trail du Mont Blanc, observational pilot study

Abstract

Introduction

The aim of this study is to evaluate the effect of napping on perceived sleepiness and cognitive performance during an ultra-trail.

Summary of facts and results

Twenty-three runners participated in our study on the Ultra Trail du Mont Blanc ® 2021 (UTMB®). Their sleepiness status (Karolinska Sleepiness Scale, KSS) and cognitive performances (reaction time, RT) were evaluated at the the kilometer 142 checkpoint (28 ± 2 hrs of race). Two groups were formed: a nap group (GS, n = 11) and a control group (GC, n = 12). Measurements were made at the entrance to the checkpoint (ENT), right after the nap (POST, only for GS) and 1 km after the checkpoint (1 km). At ENT, GS runners had a longer RT than GC (P < 0.05). There was an improvement in RT immediately after the nap in the GS group (P < 0.05). This improvement was maintained at 1 km (P < 0.001). At 1 km, there was no difference between the two groups. A decrease in the KSS of the GS group was observed between POST and 1 km (P < 0.001).

Conclusion

The participant who took a nap during the second night of UTMB had lower cognitive performances than the GC group. Beyond a long-term strategy, the perception of a lesser self-alertness seems to be a determinant in the decision making to stop for a nap. In this context, a 15 to 20 min nap, including the sleep onset duration, seems to improve cognitive performance as well as perceived sleepiness.