In a recent study published in the journal BMJ Open, an international team of researchers conducted a longitudinal study over 10 years to understand the association between physical activity and sleep duration, daytime sleepiness, and current insomnia symptoms in adults.

Study: Association between physical activity over a 10-year period and current insomnia symptoms, sleep duration and daytime sleepiness: a European population-based study. Image Credit: Ground Picture/Shutterstock.com

Background

Adequate sleep is one of the major aspects of life and health that has suffered due to the fast-paced nature of modern lives and an increase in the use of electronic devices such as mobile phones.

Sleep disturbance and insomnia have a direct impact on overall health, can increase the risk of metabolic dysfunction, cardiovascular disease, and psychiatric disorders, and impact the quality of life.

Physical activity or exercise is known to improve sleep quality, reduce symptoms of insomnia, and benefit overall health. Exercise has been associated with reduced daytime sleepiness, and low levels of physical activity are believed to increase daytime sleepiness.

However, factors such as age, gender, body mass index (BMI), general state of health, fitness levels, and type of physical activity can moderate the association between exercise and sleep quality through numerous psychological and physiological pathways.

Furthermore, there is a dearth of long-term data from studies involving large cohorts, making it difficult to decipher whether the positive impact on sleep outcomes is due to higher physical activity levels, or inadequate physical activity is due to disturbed sleep.

About the study

In the present study, the researchers aimed to assess whether the frequency, intensity, and duration of physical activity were interrelated with daytime sleepiness, disturbed sleep, and symptoms of insomnia.

The study was conducted across nine countries, twice over a span of 10 years, among adults between the ages of 39 and 67 years.

The data for this study was obtained from two follow-ups of the European Community Respiratory Health Survey. Assessments of physical activity levels were conducted using participant responses to questionnaires.

The queries aimed at determining how often the participants exercised, and the number of hours per week they needed to exercise to get to a stage where they were sweaty or out of breath.

A minimum of one hour of physical activity a week or an exercise frequency of twice a week or more was considered physically active.

Based on the change in physical activity levels between the two follow-ups, the participants were grouped into four categories — those who remained non-active, those who went from active to inactive, those who became more active, and those who maintained their physical activity levels over the 10 years of follow-up.

The  Basic Nordic Sleep Questionnaire was used to evaluate the symptoms related to disturbed sleep and insomnia. These questions addressed the occurrence and frequency of symptoms such as difficulty initiating or maintaining sleep, as well as awakening too early in the morning.

The Epworth Sleepiness Scale was used to assess daytime sleepiness. Additionally, the average sleep duration was used to classify the participants into short, normal, and long sleepers based on more than six hours, between six and nine hours, and more than nine hours of sleep, respectively.

Results

The results showed that adequate physical activity was associated with a lower incidence of either short or long sleep durations and decreased risk of some symptoms of insomnia.

Individuals who maintained adequate physical activity levels through the 10 years of follow-up were found to be less likely to report symptoms of insomnia during the follow-up.

Furthermore, persistently active individuals also reported achieving the recommended six to nine hours of sleep, and these associations were found to be significant even after adjusting for confounders such as age, sex, BMI, and smoking behavior.

On average, individuals who were persistently active over the 10 years of follow-up had lower BMI, were younger, and were male. They were also less likely to be smokers and more likely to be currently employed.

Although daytime sleepiness or symptoms such as difficulty maintaining sleep were not found to be linked to physical activity levels, smoking behavior was found to have independent associations with daytime sleepiness.

Conclusions

Overall, the findings suggested that consistent, long-term physical activity can decrease the risk of various insomnia symptoms and help achieve adequate sleep.

Furthermore, although physical activity levels did not seem to impact the occurrence of daytime sleepiness, lifestyle factors such as smoking behavior were associated with daytime sleepiness.