People who are “night owls” and have a tendency to spend more minutes sitting are less motivated to maintain an exercise schedule, according to a new study from researchers involved in the Behavioral Sleep Medicine Program at the Feinberg School of Medicine at Northwestern University in Chicago, IL.

The journal Sleep recently published the research abstract in their online supplement. The results of this new study were presented in Minneapolis, MN, at SLEEP 2014, the 28th annual meeting of the Associated Professional Sleep Societies LLC.

The Centers for Disease Control and Prevention (CDC) recommend 7-8 hours of sleep per day for adults, including the elderly. Insufficient sleep can impact people managing chronic diseases and conditions including diabetes, cardiovascular disease, obesity and depression.

The study observed 123 healthy adults who reported sleeping for at least 6.5 hours a night. Wrist actigraphy and sleep diaries were used over 7 days to measure sleep variation across the study group. Questionnaires, including the International Physical Activity Questionnaire obtained comparable estimates of physical activity together with self-reported attitudes toward exercise.

“This was a highly active sample averaging 83 minutes of vigorous activity per week,” says principal investigator Kelly Glazer Baron, PhD, associate professor of neurology and director of the Behavioral Sleep Medicine Program. “Even among those who were able to exercise, waking up late and being an evening person made it perceived as more difficult.”

The research results show that those individuals who go to bed later self-reported more minutes sitting, with time of sleep continuing to be a significant predictor of minutes sitting, after controlling for age and sleep duration.

Glazer Baron reveals:

We found that even among healthy, active individuals, sleep timing and circadian preference are related to activity patterns and attitudes toward physical activity. Waking up late and being an evening person were related to more time spent sitting, particularly on weekends and with difficulty making time to exercise.”

Participants who considered themselves to be night owls described more time sedentary and more perceived barriers to exercise, stating a shortage of time for exercise and an inability to adhere to an exercise schedule, irrespective of what time they went to sleep or woke up.

Circadian factors should be considered as an element of exercise advice, especially for less active adults, the study suggests.

Woman sleeping on exercise bikeShare on Pinterest
Participants who considered themselves as night owls described more time sedentary and more perceived barriers to exercise.

“Sleep timing should be taken into account when discussing exercise participation,” Glazer Baron adds. “We could expect that sleep timing would play an even larger role in a population that had more difficulty exercising.”

The CDC indicate that physical activity helps improve overall health and fitness and reduces the risk of many chronic diseases. They recommend that adults need at least 150 minutes of moderate intensity aerobic activity every week and 2 or more days a week of muscle-strengthening activities.

In February this year, Medical News Today published a news release on another study by Northwestern University, which suggested too much sitting is linked to major disability after 60. The study concluded that for adults 60 and older, every additional hour a day spent sitting is linked to doubling the risk of being disabled. This study was the first to highlight sedentary behavior as its own risk factor for disability and labeled the behavior almost as strong a risk factor for disability as lack of moderate exercise.