extreme violation of sleep hygiene: sleeping against the biological clock during a multiday relay event

results linear mixed model analyses showed that athletes slept on average 43 minutes longer when they slept during usual (night) times than during abnormal (day) times. in general, sleep duration decreased during the race with on average 18 minutes per period. conclusions this pilot study shows that, even under extreme violation of sleep hygiene rules, there still is an apparent effect of circadian rhythm on sleep duration in relay race athletes. background sleep hygiene is important for sleep quality and optimal performance during the day. however, it is not always possible to follow sleep hygiene requirements. in multiday relay events, athletes have to sleep immediately after physical exertion and sometimes against their biological clock. objectives in this pilot study we investigated the effect of having to sleep at an abnormal circadian time on sleep duration. patients and methods eight runners and two cyclists performing a 500 km relay race were followed. they were divided into two groups that took turns in running and resting. each group ran four times for approximately five hours while the other group slept. as a result, sleep times varied between normal and abnormal times. all athletes wore actigraphs to record the duration and onset of sleep.