A narrative review of sleep deprivation in ultra-endurance cycling

Sleep deprivation and mental health in ultra-endurance cycling

Based on these studies, acute sleep deprivation and extreme sleeping patterns are a prominent feature of ultra-endurance cycling. All of the papers included in our review indicate that ultra-endurance riders may experience sleep deprivation and intermittent or acutely short sleep periods. First-hand accounts from ultra-endurance cycling events support this; for instance, certain RAAM athletes revealed an 8-hour total sleep time across the entire event [2], as have participants in other ultra-endurance races [17]. Entrenched sociocultural attitudes amongst ultra-endurance riders could shape attendant behaviours. Whilst accentuating the importance of sleep, multiple-time winner of the Transcontinental Race, James Hayden, illustrated how deleterious perspectives still persist; sleep can be perceived as “wasting time” as compared to the “glorification” of sleep avoidance [18].

This evidence aligns with simulated Grand Tour events in elite-level cycling [19], alongside studies on ultra-endurance sporting events that span multiple days of competition. For instance, ultra-triathletes experienced severely reduced sleep and a subsequent decline in performance during a three-day race [20]. In ultramarathons, participants experienced severe sleep deprivation and hallucinations whilst competing in multiple races exceeding 322 km; a hesitancy to sleep was prevalent among these runners [21]. Further, restricted sleep was associated with a decrease in vigour in an arctic ultramarathon [22], and during the Finnmarkslop, a six-day dog sled race [23]. Lapses in attention and other deficits in cognitive function were evident in multisport endurance athletes after 36 hours of sleep-restricted competition [24].

Given the documented paradigms of extreme sleep in our review, ultra-endurance cyclists could be increasingly at-risk for negative cognitive effects and psychosocial concerns. The articles we identified primarily explored sleep deprivation in competitive performance or ergometric contexts. However, several papers did note sizable implications for riders’ mood, including increased fatigue and decreased vigour [11], alongside emotional disturbances [14]. Again, this correlates with other findings in ultra-endurance sport, which show that mood alterations can last up to a month post-race [25]. Significantly, sleep deprivation has associations with neurocognitive deficits, emotional dysregulation, and suicidality in general literature [6]. Others highlight connections between sleep deprivation, heightened stress responsivity, emotional reactivity, and impaired executive functioning and decision-making [7]. Specific environmental factors may aggravate these effects for ultra-endurance riders; intra-race, sustained exposure to physical exertion in unfamiliar terrains and adverse conditions will likely negate stress reduction strategies. Additionally, mood state can be altered by dehydration in ultra-endurance cycling competitions [26]. Further, impaired decision-making, attention, and reaction time due to sleep deprivation might enhance the possibilities for serious accidents. These scenarios could have medicolegal or forensic-psychiatric intersections, particularly if a rider is held liable for injuring fellow competitors.

From a clinical perspective, sleep deprivation can induce symptoms of mania or psychosis, like hallucinations and delusions [8, 27]. Ultra-endurance cyclists have previously reported analogous experiences [2]. Notably, in other circumstances, hallucinations from sleep deprivation have required psychopharmacological interventions and in-patient care [27]. Moreover, sleep deprivation and disrupted circadian rhythms can exacerbate pre-existing psychiatric symptoms [9, 28] and may have causal relationships with mental health issues and increased symptomatology [29]. This is significant since ultra-endurance athletes might already be vulnerable to psychopathology and distinctive risk factors; prior psychiatric diagnoses were found to be more prevalent in this community compared to the general population [30]. Thus, in our view, periods of intensive exposure to deprived or extreme patterns of sleep in ultra-endurance cycling could lead to developing or recurring psychiatric disorders.

Psychoeducation and knowledge exchanges

With these potential cognitive and psychiatric effects, we believe that increased regulatory endeavours and knowledge exchanges are necessary to uphold rider wellbeing; for us, race organisers have a duty of care to their participants. Nevertheless, the management of ultra-cycling competitions can vary from private individuals to commercial entities. This heterogeneity creates disparities, with races adopting different rubrics and policies. To counter this, WUCA has developed “Model Race Rules” [31] for race organisers. Despite containing “no restrictions on how many hours a racer may ride without off-bike rest”, these guidelines allow officials to request sleep breaks if athlete safety is compromised [31].

Researchers have underlined the importance of mental preparation for ultra-endurance cycling events [14], and companies have produced dedicated resources about sleep management (e.g., [32, 33]). However, in research about other ultra-endurance competitions, only 21% of participants indicated that they had sleep strategies intra-race [34]. For safeguarding purposes, greater efforts should be made to develop scientific consensus on the topic of intra-race sleep in ultra-endurance cycling, similar to the heat training initiatives of the International Olympic Committee [35], which also constitutes a significant hazard during ultra-endurance events. Standardised educational materials should be made available on race websites, as well as disseminated in the pre-race period as a mandatory part of the signup process. Presently, as our review illustrates, studies about the psychiatric and psychological effects of sleep patterns in ultra-endurance cycling are scarce and extant research tends to have limited sample sizes. Accordingly, more longitudinal research and larger scale studies are needed to understand how sleep deprivation affects the mental health and cognitive function of athletes, both intra-race and post-race. Such investigations are necessary to inform evidence-based approaches, event regulations, and institutional support, especially as different race durations may require tailored guidelines.

We further advise that all ultra-endurance cycling events should be staffed with qualified mental healthcare practitioners, who could be called upon to help both athlete and crew assess potential risks due to sleep deprivation. To the authors’ knowledge, there is no definitive evidence base directly correlating increased intra-race sleep with faster race times (several studies in our review suggest that competitive performance levels were unaffected [10, 12, 13, 16]). Resultantly in our opinion, it is unlikely that riders will be motivated to voluntarily prioritise their mental health during races, although it has been found that athletes can still have successful race results in ultra-endurance cycling with an increased emphasis on sleep [36]. Therefore, we recommend that relevant governing bodies could consider prioritising the physical and mental wellbeing of racers by implementing regulations such as set stages for multi-day cycling events.

Given the associated risks of ultra-endurance cycling, notions of individual responsibility and personal choice are significant. Since sleep patterns may be an important variable in predicting sporting success in these races, a lack of knowledge could increase possibilities for psychotropic self-medication to alter sleeping habits, potentially leading to longer-term health problems for athletes. Moreover, improving comprehension about the psychopathological paradigms of sleep deprivation may influence individual decisions to join these events and could prevent psychiatrically vulnerable individuals from participating. That said, mental health stigma persists in competitive environments [30], as do negative conceptions about sleep in ultra-endurance cycling [18], which may undermine awareness campaigns. Akin to other sports, entrenched sociocultural perspectives are often difficult to modulate [37]. Nonetheless, increased knowledge exchanges, alongside bespoke educational campaigns, could enhance mental health literacy in ultra-endurance riders; to that end, community-relevant platforms, like the Global Cycling Network, could help promote these issues [38]. This may stimulate open discussions about balancing healthy sleeping and competitive performance.

Limitations

We considered our search strategy to be the best-available method to investigate this underexamined topic, as connections between sleep deprivation and mental health in ultra-endurance cycling are limited. Nonetheless, our narrative review has several limitations.

Evidence scarcity commonly prevents comprehensive systematic reviews [39], but our non-systematic approach may have neglected certain studies. Further, narrative reviews are prone to selection bias [40] and reproducibility concerns [41], which cannot be disregarded within our methods. By only including studies with empirical observations, we may have introduced potential biases or excluded other relevant scientific contributions. However, this was done with the aim of holistically collating papers based on primary evidence. The articles captured in our review tend to have a small sample size, but this reflects the scarcity of comprehensive research in this area; large scale investigations are required to inform requisite guidelines and initiatives, as we have discussed. Additionally, given we adopted a ten-year timeframe some studies could have been overlooked. Yet, in our opinion, this ensured that we captured up-to-date evidence in this area.