Researchers from the French University of Littoral Côte d'Opale studied the sleeping strategies of 23 ultracycling athletes during the Race Across France in June 2024. The race covered 2,588 kilometres with 29,250 metres of elevation gain from Lille to Mandelieu-la-Napoule. The participants had to complete the route within 240 hours and plan their own sleep and nutrition strategies.
The researchers fitted the cyclists with wrist-mounted acceleration sensors and asked them to rate their fatigue levels every four hours. The athletes undertook cognitive tests at five checkpoints. Of the original 40 volunteers, 23 participants completed the protocol in full. Ten riders withdrew from the race, whilst for a further seven, the measuring devices or smartphone apps failed.
Sleep duration in ultracycling
Analysis of the acceleration sensors revealed an average total sleep time of 228 minutes per 24-hour period. Individual figures ranged from 95 to 306 minutes. The participants took between 142.1 and 214.2 hours to complete the route, averaging 190.7 hours. They spent between five and eight nights on the race.
Given the small number of participants, the scientific significance is limited – but the ultracycling study did find a correlation between sleep duration and finishing position. Riders with a higher average sleep duration per 24 hours achieved better rankings. It might therefore make sense to take targeted rest breaks in order to continue riding feeling more refreshed and at a faster pace. Conversely, those who sleep too little ultimately perform less well. It goes without saying that too much sleep would also have a negative impact on one’s position in the rankings.
The body’s internal biological clock and tiredness
The propensity to sleep followed a distinct 24-hour rhythm. The greatest tendency to sleep occurred between midnight and 4 am. Fatigue levels also showed a clear circadian rhythm, peaking between 11 pm and midnight. Riders who slept for less than 5 hours and 29 minutes per day reported a significant increase in tiredness as the race progressed. This threshold appears to mark a critical minimum duration of sleep required to maintain alertness during endurance events lasting several days.
Cognitive performance and reaction times
A lack of sleep had a demonstrable effect on mental abilities. The researchers used a simplified version of the Go/No-Go reversal test to measure cognitive flexibility. This test assesses the ability to respond to feedback and adjust behaviour following a reversal of the task instructions. Participants who had had less sleep between the tests showed greater declines in performance when distinguishing between ‘Go’ and ‘No-Go’ stimuli.
Reaction times slowed as sleep debt increased. This effect was particularly pronounced between 5 am and 9 am. The fastest reaction times occurred between 5 pm and 9 pm. This circadian rhythm, also known as the internal biological clock, influenced cognitive performance regardless of total sleep duration.
Drivers who slept an average of 2.91 hours showed an improvement in their ability to distinguish between stimuli during the pre-reversal phase over the course of the days. For those who slept for 7.02 hours, this improvement occurred in the post-reversal phase. Reaction times increased with an average of 4.38 hours’ sleep in the pre-reversal phase and 4.09 hours in the post-reversal phase.
Practical implications for athletes
The results show that strategic sleep management is crucial for performance in ultracycling. Athletes should, where possible, align their rest periods with the rhythm of their internal biological clock. The hours between midnight and 4 am offer the best quality of sleep.
The study also has safety implications. Insufficient sleep increases the risk of accidents not only for the driver themselves, but also for other road users. Organisers could introduce compulsory training on fatigue management and provide safe rest areas. Medical teams should consider structured recovery protocols after the race.
Methodological limitations
The relatively small sample size and the dropout rate during the race limit the relevance of the findings. No universally applicable scientific conclusions can be drawn from the ultracycling study. Given that in ultracycling the nature of the races, their duration and the demands of the routes vary greatly, this is to be expected. In any case, the study serves as a reminder that a well-thought-out sleep strategy is important. This applies both to the timing of sleep and to its duration.
Applicability to other areas
The concept of ‘Wakefulness Made Good’, which originally stems from offshore sailing, can be applied to ultracycling. Athletes must strike a balance between alertness and the functional impairment caused by sleep deprivation. Short naps and efficient sleep management help to maintain cognitive and physical performance under sustained exertion. It is not without reason that short power naps are widely practised in ultracycling.
Kristian Bauer
Editor