Early risers and night owls: A sleep expert explains the best time to exercise

Some of the mechanisms by which exercise has a positive impact include reducing factors that can disrupt sleep, such as anxiety and obesity; and assisting the circadian rhythm, the natural sleep-wake cycle (to support consistent patterns).

Recommendations, historically, included avoiding exercise close to bedtime in case sleep was disrupted by raising body temperature, for example. However, the evidence is not consistent that working out late in the day is problematic – although it might be prudent to avoid vigorous exercise in the hour before you want to fall asleep.

As to whether advice should differ for larks, those ‘morning types’ who function at their best earlier in the day, as compared to owls, ‘evening types’ who function best later in the day, the answer depends, in part, on whether there is a desire to shift sleep timing.

Our body clocks are controlled by factors from within our bodies, and tweaked by influences from the world around us, such as the timing of exercise and our light exposure. Less is known about the impact of exercise on tweaking the body clock than light.

However, it is possible that if an ‘owl’ is keen to fall asleep and wake up earlier (because, for example, of a specific work schedule), exercising early in the day – and with simultaneous light exposure – may help. On the other hand, if a ‘lark’ wishes to go to bed later (to allow for a longer evening), they might benefit from exercising later in the day, at some point between 7pm and 10pm, particularly if there is an exposure to light at the same time.

There could be an interaction between exercise timing, whether you’re a lark or an owl, and sleep. One study found that exercising later in the day was more associated with a delayed sleep time for ‘morning’ than ‘evening’ types. A busy lifestyle can make it tricky for people to schedule exercise; if evening provides that opportunity, then exercise benefits outweigh the risks.

Read more:

• What’s the best thing to do when you can’t sleep?
• I’m addicted to the gym, but I have a cold. Can I still exercise?
• Why do I always get an energy crash in the afternoon?
• Do the benefits of exercise wear off as your body gets used to it?

Asked by: Sienna Harris, via email

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