Among adults in the United States, an estimated 35 to 40% of the population has problems with falling asleep or with daytime sleepiness.  Paul Loprinzi, from Bellarmine University (Kentucky, USA), and colleagues studied a nationally representative sample of more than 2,600 men and women, ages 18-85 years, adding evidence to mounting research showing the importance of exercise to a number of health factors.  Specifically, the team found that 150 minutes of moderate to vigorous activity a week, which is the national guideline, provided a 65% improvement in sleep quality. People also said they felt less sleepy during the day, compared to those with less physical activity.  Concluding that: “Objectively-measured physical activity was associated with several self-reported sleeping-related parameters,” the study authors note that: “Those who were more active fell asleep quicker.”