Vigorous Exercise May Improve Deep Sleep, Study Finds

Physical activity’s impact on sleep quality has been discussed at length, with a variety of demographics, exercise routines, and habits studied.

One study found that certain exercise styles can have a positive impact on the sleep quality of middle-aged, previously sedentary adults. While having fewer bad dreams, getting up to use the bathroom less frequently, and easier breathing are all worthwhile sleep goals, EEG (electroencephalogram) recordings can shed light on exercise’s impact on objective sleep quality.

This includes time spent in SWS (slow-wave sleep), more commonly referred to as deep sleep. Considered to be the most restorative sleep, a night of quality SWS can lead to better overall function the next day. A recent study examined the impact of vigorous exercise on both subjective sleep quality and SWS.

What Was Studied?

Nine healthy young men, who had not exercised regularly prior to the study, performed a 60-minute treadmill workout six hours prior to a prescribed bedtime. The workout was performed at 60% V02 max.

The study controlled for diet, sleep conditions, and both alcohol and caffeine consumption. An internal sensor measured various metabolic changes, including core body temperature, while participants were fitted for electrodes to evaluate their sleep cycles.

What Did the Study Find?

Participants reported worse sleep quality based on their own subjective assessment after exercise, as compared to a controlled trial. However, EEG readings suggested that the physiologic processes that induce SWS were enhanced by vigorous exercise.  

The Benefits of Exercise on Sleep Quality

Don’t let the conclusion of worse sleep quality after vigorous exercise keep you from your next run or jog: The benefits far outweigh the potential feeling of grogginess the next morning. 

The study authors are quick to point out that this single bout of exercise is one of its limitations. It’s not uncommon for muscle soreness or other feelings of bodily discomfort to interfere with sleep. Trying to sleep in unfamiliar conditions can also make it difficult to get a good night’s sleep.

If this level of working out isn’t a habit, it may take time for your body to adjust.

Other recent research revealed that sedentary adults had improved sleep quality after a 12-week exercise intervention, while another study suggests that a protocol of as short as four weeks can benefit sleep quality in young women. Both suggest that the reciprocal relationship between sleep and exercise is strengthened over time. 

While a single study with a relatively tiny sample size might demonstrate that intense exercise can negatively impact subjective sleep quality, don’t lose sleep over it: Fitness and nutrition experts agree that the two go hand-in-hand in improving overall health and managing stress.  

“As humans, we all have varying degrees of life stress. And sometimes that stress and its management (or lack thereof) can impair our sleep patterns,” says Dave Callari, NASM-CPT, owner of RPM Nutrition and Fitness.

“Engaging in regular exercise can help check all the health boxes: increased muscle mass, bone density, cardiovascular capacity, improved blood pressure, and if your nutrition allows for it, fat loss,” continues Callari.

He also notes, “This will generally contribute to feelings of well-being, and to that point can help alleviate feelings of stress you might have from a tough day at work or home. Better stress management and less anxiety can lead to better sleep.”

Erik Bustillo, MS, RD, FISSN, CSC, CPT, co-vice president of the International Society of Sports Nutrition, echoes this sentiment.

“Optimal sleep is crucial for performance. Although, when it comes to performance, nothing is more important than the performance itself. For example, if you want to be a better 400m runner, you have to run and physically train because you cannot ‘sleep’ your way into becoming better at running.”

Bustillo does note that while the practice of performance is important, sleep impacts recovery, brain function, muscle function, and hormone response. “I would place it equally with diet, right after training itself,” he says.

How Do I Determine My Sleep Quality?

If you’re meeting (or exceeding) recommended guidelines for physical activity, reaching your sleep goals, and subjectively feeling refreshed, you may assume your sleep quality is, objectively, good.

While this may be the case, an outside perspective can help you determine how good (or bad) your sleep quality really is.

“I have an app called Sleep Cycle,” Callari mentions. The app sets a soothing alarm and tracks your sleep, ultimately giving you a better idea of your sleep quality. “It isn’t super accurate,” Callari notes, “but it gives you a decent overview of your night.”