Strenuous exercise before bed has long been discouraged, but researchers at the University of Otago have found that short, light activities can lead to better sleep.

Exercise in the Evening Promotes Sleep Quality

In a world-first study published in BMJ Open Sport & Exercise Medicine and funded by the Health Research Council, participants completed two four-hour evening intervention sessions in which they sat for long periods and sitting was interrupted every half hour by three-minute exercise breaks. The researchers found that participants slept 30 minutes longer after the activity breaks. Lead author Jennifer Gale, a PhD student in the Department of Human Nutrition, explains that prolonged sitting is associated with an increased risk of diabetes, cardiovascular disease and death. In their previous studies, researchers had found that getting up and moving for 2-3 minutes every 30 minutes reduced the amount of sugar and fat in the blood after a meal.

However, many sleep guidelines discourage prolonged or vigorous exercise in the hours before bedtime. The experts therefore wanted to find out what happens if you repeatedly engage in very short, light exercise in the evening. The movement intervention comprised three exercises: chair squats, calf raises and standing leg raises with hip extension of the straight leg. These simple bodyweight exercises were chosen because they don’t require equipment or a lot of space, and you can do them without interrupting the TV show you’re watching.

The fact that this exercise led to longer sleep is important because insufficient sleep can have a negative impact on nutrition and cause serious health problems. Although intense exercise before sleep is often cautioned against because it can increase body temperature and heart rate, the researchers say it may be time to revise these guidelines, as the study showed that regularly breaking up prolonged sitting is a promising health intervention.

Which Type of Exercise is Better for a Good Night’s Sleep?

Although both aerobic exercise (endurance exercise) and resistance exercise (strength training) are important for overall health, research suggests that resistance exercise may be better for helping you fall asleep at night. Previous research has confirmed that too little sleep (the recommended amount of sleep for adults is seven to eight hours per day) or poor quality sleep increases the risk of high blood pressure, high cholesterol and atherosclerosis, which is the buildup of fat in the arteries. Too little sleep has been linked to weight gain, diabetes and inflammation, all of which can exacerbate cardiovascular disease. Too much or too little sleep has also been shown to increase the risk of stroke, heart attack and death.

The study involved 386 adults who met the criteria for being overweight or obese, i.e. had a body mass index of 25-40 kg/m². Participants were inactive and had elevated blood pressure ranging from 120-139 mm Hg systolic (upper range) to 80-89 mm Hg diastolic (lower range). Participants were randomly assigned to a no-exercise group (for comparison) or one of three exercise groups (aerobic exercise only, strength training only or combined aerobic and strength training) for 12 months. All participants in the exercise groups participated in supervised 60-minute exercise sessions three times a week, with the combined exercise group completing 30 minutes of cardio and 30 minutes of strength training.

Participants in the aerobic exercise group could choose between treadmills, recumbent bikes or elliptical trainers to do their aerobic exercise at each session. The researchers monitored their heart rates to keep them continuously within the prescribed heart rate range for moderate to heavy exercise. The resistance training group completed their sets and repetitions on 12 resistance machines to work all major muscle groups in one session. The machines included leg press, chest press, lat pulldown, leg curl, leg extension, bicep curl, tricep press, shoulder press, abdominal press, back extension, trunk rotation and hip abduction. The participants completed three sets of 8 to 16 repetitions at 50-80% of their unilateral maximum power. The combination group completed 30 minutes of aerobic exercise at moderate to high intensity followed by two sets of 8 to 16 repetitions on 9 machines instead of 12.

Significant Improvement in Sleep Duration and Sleep Efficiency

More than one-third (35%) of study participants had poor sleep quality at baseline, and among the 42% of participants who did not get at least 7 hours of sleep at baseline, sleep duration in the resistance group increased by an average of 40 minutes over 12 months, compared with an increase of about 23 minutes in the aerobic group, about 17 minutes in the combined training group, and about 15 minutes in the control group, and sleep efficiency increased in the resistance training and combined training groups, but not in the aerobic training or no training group. Sleep latency decreased slightly by 3 minutes in the resistance training only group, while latency did not change significantly in the other participant groups. Sleep quality and sleep disturbances improved slightly in all groups, even in the group that did not train. Overall, resistance training was found to significantly improve sleep duration and sleep efficiency. Based on these results, interventions that focus on resistance training could be a new way to promote better sleep and improve cardiovascular health.