Sleep quality is an important clinical issue for two major reasons. The first reason is that at least 19% of the population has trouble sleeping. The second reason is that poor sleep quality is an important symptom of many medical disorders. However, surprisingly there is very little research on the impact of exercise on sleep quality.
One study I can recall that has examined this topic directly was performed by a group of Taiwanise scientists (presented at 2002 American College of Sports Medicine’s Annual Convention). After examining the reported sleeping habits of 175 healthy students, these researchers identified the students that had trouble sleeping, then asked all of them to perform a series of fitness tests. The exercise testing protocol was similar to an obstacle course workout.
According to the results, the students that performed best on the fitness tests were the ones that reported no sleep problems. Interestingly, these students also reported the highest levels of physical activity during the day. So there definitely appears to be a link between fitness/activity levels and sleep quality.
From personal experience, I’ve regularly found that if I don’t exercise for more than a couple of days, I have trouble falling asleep at night. I also find my sleep quality is best when I’m training consistently hard and have achieved a high level of aerobic fitness. So while this research does not directly substantiate the notion that intense exercise improves sleep quality, I feel there definitely is a link between exercise performance, physical fitness and sleep quality.
