Today, Matt focuses on how the type, intensity, and duration of exercise affect its impact on sleep. A study of middle-aged adults split its active group into three subgroups: moderate-intensity aerobic exercise, high-intensity aerobic exercise, and moderate-to-intense weight/resistance training. The groups performing aerobic exercise got more beneficial sleep effects, while surprisingly, the greatest improvement was in the moderate rather than the high-intensity group. These findings replicate those from the National Sleep Survey, indicating a Goldilocks syndrome in finding just the right level of exercise to benefit sleep.

Regarding types of exercise, studies show that cycling produces the most robust improvements in deep non-REM sleep. Meanwhile, more mind-body-based exercises provide equal if not greater benefits in sleep quality than traditional forms of physical activity. 

Another factor to consider is duration of exercise. Some studies have discovered that more minutes of acute exercise in a single bout produce larger benefits in several sleep metrics, including deep non-REM sleep, the speed of falling asleep, and the amount of sleep overall. However, it’s also been found that progressively longer bouts of exercise can be associated with a moderate reduction in the amount of REM sleep, though Matt states that it’s such a modest reduction as not to be concerning.

The final element is the intensity of exercise. Early studies found indications that more intense exercise gave a greater improvement in sleep quality, though the difference in improvement was minimal. Later, more comprehensive studies have reinforced this, indicating that it is not necessary to go to the extremes of physical exertion to get most of the sleep benefits exercise provides.

Currently, the reason why exercise promotes better sleep is unknown, but Matt offers several tenable possibilities, including that exercise promotes the release of immune factors and growth hormone. He also suggests a more “out there” explanation in the form of a chemical called brain-derived neurotrophic factor (BDNF), the release of which is facilitated by exercise, and which is known to increase deep non-REM sleep.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

Today's podcast is supported by InsideTracker, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link.  InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and also offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you. 

Another sponsor this week is the biochemical electrolyte drink company LMNT, and they are very kindly offering eight free sample packs when you purchase any one of their orders at drinklmnt.com/mattwalker. LMNT is an electrolyte sports drink that I can get behind - it's created from the basis of science, and it has no sugar, no coloring, and no artificial ingredients – all qualities that are so important to maintaining your blood biochemical balance. If you want to give LMNT a try, just head on over to drinklmnt.com/mattwalker and get your eight free samples with your first purchase. 

And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.