Regular physical activity can lead to less daytime fatigue, according to a study published in the journal Mental Health and Physical Activity.

Researchers at Oregon State University reviewed data from 2,500 men and women between the ages of 18 and 85 who had worn devices measuring their physical activity for a week in 2005.

Those who exercised the recommended 150 minutes (moderate) or 75 minutes (vigorous) per week were 65 percent less likely to feel sleepy during the day, compared to those who exercised less. They were also 68 percent less likely to report having leg cramps and 45 percent less likely to report difficulty concentrating.

Exactly how exercise is related to sleep is unclear. Some experts believe exercise helps alleviate stress, anxiety and depression, which can also affect sleep. Others suggest that when you burn more energy through exercising, your body sleeps more efficiently to recover.

Over one-third of adults in the U.S. have difficulty falling asleep or staying alert during the day, researchers noted.