Physiology Friday Issue #4: Strength Training Outperforms Aerobic Exercise for Promoting Sleep
Happy Physiology Friday!
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Trying to sleep better? Many people are, and there is no shortage of ways (proven or otherwise) to boost the time you spend sleeping and your sleep quality (how well you sleep). These strategies include sleep supplements, bedtime meditation apps and white noise machines, and even temperature-controlled mattress covers and comforters.
But better sleep doesn’t need to involve high-tech gadgets or supplements. In fact, exercise may be one of the best ways to promote a good night of sleep and healthy sleep patterns. This may have to do with the effects of physical exertion on sleep (you’ll sleep better if you’re exhausted from the day’s workout) or the fact that good sleep can increase the motivation to exercise — and those who enjoy working out typically dedicate themselves to a rigorous sleep schedule for this reason.
Exercise may also have direct effects on sleep quantity and quality, though the exact mechanisms aren’t quite clear. Circadian rhythms may be involved, as could effects on hormones and body temperature.
What type of exercise leads to the best sleep? Is a heavy strength training routine better than endurance exercise for promoting healthy sleep habits?
An abstract presented at the 2022 American Heart Association Epidemiology: Lifestyle Scientific Sessions meeting investigated the best training regimen for improving sleep.
Participants were adults with hypertension at an increased risk for cardiovascular disease. They were split up into four groups and randomly assigned to an exercise condition: resistance exercise, aerobic exercise, combined exercise (resistance and aerobic) or a control (no exercise) condition.
For 1 year, participants completed their assigned exercise 3 times per week for 1 hour each day (the combined group did 30 minutes of resistance and 30 minutes of aerobic exercise). The exercise intensity was prescribed to be 50–80% of their maximum intensity.
At baseline and 1 year, participants’ sleep was assessed using a questionnaire that provided information about their sleep quality, sleep duration, sleep efficiency, how long it took them to fall asleep (sleep latency), and sleep disturbances.
Sleep quality improved and sleep disturbances were reduced in all of the groups — control group included. Perhaps a result of their knowledge of being included in a sleep study?
Resistance exercise was the only type of exercise to lead to longer sleep. Specifically, at 1 year, participants in this group extended their sleep duration by 17 minutes, while the other groups did not experience significant changes in sleep duration. It is important to note that this increase occurred only in participants with a baseline sleep duration under 7 hours (i.e. short sleepers).
Sleep efficiency — the amount of time spent sleeping divided by the time spent in bed — also increased in the resistance exercise group. The combined aerobic + resistance exercise group increased their sleep efficiency as well. The resistance exercise group also decreased the time it took them to fall asleep by 3 minutes.
These are some of the first data I’ve seen on the beneficial effects of resistance exercise (i.e. strength or weight training) on sleep, though there have been some studies showing that aerobic exercise can promote better sleep the following night.
Though sleep duration only increased by 17 minutes in the resistance exercise group, any improvement is beneficial, since these individuals were not meeting the sleep recommendations for older adults (>7 hours) at baseline. 17 minutes could be enough to get someone over this threshold.
What makes these results especially significant is that participants were a group at risk for cardiovascular disease. Short sleep duration and poor sleep quality are both known to elevate several CVD risk factors and increase one’s risk for disease.
Exercise is also one of the best ways to improve cardiovascular health. This is a win-win scenario. Better cardiovascular health from exercise promotes better sleep, which in turn promotes even better cardiovascular health. Good sleep also promotes healthier exercise habits. Quite the reciprocal relationship.
It isn’t clear to me why the aerobic exercise group did not see improvements in sleep throughout the year-long study, nor why resistance exercise was particularly beneficial. The mechanisms for this may be something to explore in a future study.
Does one type of exercise typically lead to better sleep in your experience? Are you tired or wired after strength or aerobic exercise training? I’d love to hear about it in the comments below or on social media!
Thanks for reading. See you next Friday.