Night Owls, Morning Larks, and Barbells

Some local night owls pumping iron.

Are you an early riser, or a night owl? Given the timing of swim events at the 2016 Olympic Games in Rio, which frequently start at 10pm and don't wrap up until after midnight, the answer to this question may very well be on the minds of some athletes. It turns out the sleeping habits of these athletes might make all the difference in their performance. 

Like animals, plants, fungi, and even some bacteria around us, humans have a built-in internal clock.  These circadian rhythms guide many biological processes throughout the day, including our sleep cycles.  Although humans are diurnal animals, there is a great deal of variation in our individual sleep preferences. Some of us are ‘morning larks’, who naturally wake up early to greet the day, while others are more ‘night owls’, opting for activities later in the evening. So do these ingrained preferences affect the performance of Olympic athletes in Rio, or our more modest workouts at the gym? 

Researchers at the University of Birmingham sought to understand just that. For the study, 121 athletes were given a detailed questionnaire to gauge their ‘circadian phenotype’, or sleep patterns. Approximately 28% of subjects were early risers, 24% were night owls, and the remaining 48% were somewhere in between. The average wake-up times, bedtimes, and amount of sleep between each group was statistically different, suggesting that among this group of subjects, there were three unique circadian phenotypes.

From this group of athletes, 20 representative age- and fitness- matched subjects were selected to perform cardiovascular endurance tests at six different times during the day, all while keeping detailed sleep diaries. On average, the athletes performed best at 4pm and 7pm, and worst at 7am. But when the circadian phenotype was considered, the time of peak performance depended on whether the athletes were early, intermediate, or late risers. Early risers performed best at around 12:15pm, intermediates at 3:45pm, and late risers at 7:40 pm.

In the course of a day, the performance of the individual athletes varied. But do different circadian phenotypes suffer equally when they perform outside their optimal time? At most, early and intermediate risers suffered a 10% reduction in fitness scores. Late risers, however, faced up to a 26% reduction in fitness compared to their peak performance. It seems that night owl athletes face a potentially larger handicap than their earlier-rising counterparts, when they perform at sub-optimal times.

So is it just a matter of being awake for a certain amount of time to maximize your performance? According to the researchers, not so much. The peak performance time of early and intermediate risers was around 6 hours post wake up. The late risers, however, performed best about 11 hours post wakeup. 

So the next time you're scheduling your workout, you might just want to consider if you're a morning lark, a night owl, or something in between. And if you find yourself competing at the Olympics, particularly if you're a night owl with an event early in the morning, perhaps some additional sleep training is in order.