How Do Morning Workouts Affect Sleep?

Ever wondered how morning workouts affect your sleep? A new study in the European Journal of Sport Science, from researchers in Australia (including Shona Halson, the head of recovery at the Australian Institute of Sport) tackles this question. The study was fairly straightforward: they simply strapped wrist-worn sleep monitors on a training group of seven elite swimmers during a 14-day period of intense training. On 12 of those days, the swimmers had 6am workouts scheduled; the other two days were rest days.

What jumps out, not surprisingly, is that the swimmers got less sleep when they had early workouts – way less sleep, in fact. The numbers are pretty stark: they spent 7.7 hours in bed before training days, and 9.3 hours in bed before rest days. But that’s not the whole story: according to their sleep monitors, they actually only slept for 5.4 hours before training days, compared to 7.1 hours before rest days. That’s because they took longer to get to sleep on those nights (41 minutes versus 32 minutes), and spent more time awake in bed. That’s at least in part because they were making an effort to get to bed earlier before training days, which makes it harder to get to sleep. It may also have to do with anxiety and stress about the upcoming workouts.

The funny thing, as the authors of the paper point out, is that these are full-time athletes who have no particular need to train at 6am – that’s just what swimmers (and rowers and triathletes, among others) do, partly as a legacy from a time when athletes weren’t full-time. It seems pretty clear that moving the workouts an hour or two later would help these athletes get more sleep, and probably help them perform better.

So what does that mean for the rest of us? If you’ve got a job and family, you’re probably doing 6am workouts because you have to, not because you want to. The biggest thing that jumps out at me in this data is the later bed times before rest days. If you’re going to bed after midnight every weekend, that makes it harder to fall asleep when you need to on the other nights. You’re basically going in and out of jet lag once a week. Now, these swimmers were young Aussies with an average of 22.5, so perhaps it’s unreasonable to suggest that they should be in bed by 10pm every night! But if you’re trying to make early workouts work for you, then I think one of the most effective things you can do is aim for a consistent bedtime even on nights when you don’t have an early workout, so that your body gets into a routine where the early wake-up isn’t a shock. Is that trade-off worthwhile? That’s something only you can decide.

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