You probably don’t weight train to improve your sleep habits. It’s more likely you do it to slow down muscle loss, build strength, and look fabulous in a pair of leggings! But better sleep may be an additional perk of working your body against resistance. First, we know that quality sleep is vital for health. Poor quality and inadequate sleep are linked to obesity, insulin resistance, and a higher risk of cardiovascular disease, Alzheimer’s disease, and type 2 diabetes. In fact, risks start to rise when people sleep less than 6 hours per night.
Unfortunately, problems falling asleep and staying asleep are common. Studies show that 1 in 3 adults suffers from periods of insomnia. Up to 20% have periods of longer-term insomnia, and around 10% have chronic insomnia where they have problems falling asleep at least 3 times weekly. Research also shows that physical activity improves sleep quality in people with insomnia. According to studies, exercise helps people fall asleep more quickly, sleep longer, and enjoy better quality sleep after one to six months of training. However, most of the studies focus on walking and other forms of moderate-intensity exercise. Can strength training improve sleep quality too?
Strength Training and Sleep Quality Put to the Test
In a study carried out by researchers at Appalachian State University, researchers asked 24 healthy college students to do 30-minute, whole body strength training routines at varying times of the day. They also monitored their nighttime sleep patterns. What they found were the participants who strength trained fell asleep sooner. The benefits were greater when the students trained in the morning than at night. When they strength trained early, they fell asleep an average of 45 minutes faster. But, when they trained in the evening, they drifted off to sleep only 15 minutes faster. So, morning workouts may have an advantage in terms of improving sleep quality.
In another study, 36 older men were divided into an exercise and a control group. The men in the exercise group strength trained 3 times weekly for 12 weeks. The control group didn’t exercise. The researchers monitored the sleep quality of the subjects using a questionnaire called the Pittsburgh Sleep Quality Index (PSQI).
The results? The men who strength trained experienced significant improvements in sleep quality. Plus, their psychomotor performance improved significantly by the end of the study.
But how does resistance training improve sleep? Based on one small study, strength training increases the amount of adenosine in the brain. That, in turn, may have a calming effect. In fact, caffeine hypes you up by blocking the activity of adenosine so you feel more motivated, focused, and alert and less sleeping after a jolt of caffeine. Adenosine has the opposite effect of caffeine. It creates a brain environment that promotes sleep. Of course, there may be other mechanisms by which strength training improves sleep as well. The exact reason strength training helps you fall and stay asleep isn’t completely understood.
The Best Time to Exercise for Sleep
Although some studies suggest that exercising any time of day improves sleep, some of the studies that focus on aerobic training suggest that morning workouts have an edge. Exercise, especially intense exercise, activates your sympathetic or “fight or flight” nervous system. These hormones increase your heart rate and blood pressure. Being in fight or flight mode can make it difficult to fall asleep. If you have an intense strength-training workout schedule, best to do it in the morning if you’re trying to maximize sleep quality.
You May Not See Results Right Away
Based on the studies that are out there, exercise may not improve your sleep quality right away. A study published in the Journal of Clinical Sleep Medicine showed that participants didn’t report improvements in sleep quality until they had exercised an average of 4 months. So, don’t expect an exercise session to improve your sleep quality the same night. Regular, consistent training contributes more to sleep quality than a one-off workout.
For Better Sleep
There’s more evidence to support moderate-intensity aerobic exercise for sleep than strength training. But strength workouts may benefit sleep quality as well. The important thing is to exercise consistently and, if possible, earlier in the day, as most evidence supports morning workouts for better sleep. The drawback to strength training in the morning is it can impact your strength. Research shows that we’re strongest in the late afternoon and weakest in the morning. If you do train with weights in the morning, always do a thorough warm-up.
If you have back pain, approach morning workouts with caution. The discs in your spine absorb water at night and this causes them to expand in size, along with the surrounding connective tissue. In fact, you’re a bit taller in the morning than at night due to the expansion of these discs. Once you wake up and get moving, the discs lose some of this water. If you train with heavy weights early in the morning, your spine will still be expanded and stiff. Lifting under these conditions could place you at risk of a back injury, especially if you work with heavy weights. Also, avoid sudden twists and turns, especially if you train first thing in the morning.
The Bottom Line
Exercise, in general, improves sleep quality and seems to do it regardless of when you train. But you’ll likely enjoy the most benefits if you work out earlier in the day than right before bedtime. Strength-training may also be beneficial for sleep, although studies looking at this are fewer. At the very least, it’s safer than taking a sleeping medication!
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