A recent study published in Scientific Reports examines the effect of pulmonary rehabilitation (PR) on sleep efficiency (SE) in common obstructive pulmonary disease (COPD) patients.

Study: Pulmonary rehabilitation improves sleep efficiency measured by actigraphy in poorly sleeping COPD patients. Image Credit: Tridsanu Thopet / Shutterstock.com

How does COPD affect sleep?

Patients with COPD often experience chronic insomnia, with around 50% reporting unrefreshing sleep or difficulty falling or staying asleep. Notably, this prevalence is twice that in the general population and might be attributed to numerous factors, such as reduced bright light exposure or physical activity (PA) and nocturnal dyspnea.

COPD medication and nocturnal dyspnea can deteriorate sleep. Anxiety and depression, both of which are common in COPD patients, can also contribute to poor sleep.

A recent study reported an association between low activity and sleep disturbance in COPD using actigraphy. Whether poor sleep results in low physical activity or vice versa in COPD remains unclear.

Nevertheless, increasing PA in insomniacs has been reported to enhance sleep quality. PR is also recommended for COPD and includes tailored therapies, such as education, behavioral changes, and exercise to improve psychological and physical conditions. Studies suggest that PR decreases anxiety, hospitalization, healthcare costs, and depression, while also improving an individual’s quality of life.

About the study

The present study assesses PR effects on SE in COPD patients. Adults with moderate or severe COPD eligible for PR were recruited.

Exclusion criteria included obstructive sleep apnea syndrome, inability to perform PR or other activities, and PR duration exceeding five months. The researchers evaluated sleep and exercise at baseline and the end of PR.

Exercise training was performed on an ergometer. The six-minute walk test was performed with continuous monitoring of heart frequency and peripheral oxygen saturation (SpO₂).

Energy expenditure and objective activity were assessed using a wearable activity monitor. Built-in sensors captured data on heat flux, galvanic skin response, accelerometer, and skin temperature.

The device was worn 24 hours a day for seven days with a few exceptions, such as while showering. Data from five days, which included four weekdays and one weekend, were analyzed.

Activity levels were reported as the mean daily count for steps taken. Activity was also evaluated as the average metabolic equivalent of tasks and total energy expenditure.

Total sleep time, SE, and time in bed were determined using actigraphy. The Pittsburgh sleep quality index (PSQI) was used to assess sleep quantity and quality, in which higher scores indicate poor sleep quality.

Anxiety and depression were assessed using the hospital anxiety depression scale comprising two sub-scales. Scores greater than 11 on either sub-scale indicated significant psychologic comorbidity.

The St. George respiratory questionnaire was used to evaluate the quality of life, with higher scores reflecting more limitations. Breathlessness was assessed using a modified medical research council dyspnea scale.

The PR program comprised 30 sessions. Physical training was adapted to patients’ capacities and modified based on symptoms and improvements.

PR involved training on endurance and muscle reinforcement. All study participants also received therapeutic education and psychological support from the PR program.

Study findings

Seventy-four patients were screened from November 2017 to December 2021, of whom 61 patients were included but only 31 ultimately completed the study procedure. Participant drop-out was mainly due to COPD exacerbations, poor compliance, other acute diseases, or death. The average age of the study cohort was 64, 68% of whom were male.

Significant improvements were evident in the average exercise capacity of patients after PR. The prevalence of poor sleep quality was 77% and 61% based on actigraphy and PSQI, respectively.

Twenty-four patients with reduced baseline SE showed significantly increased SE after PR, with no changes in PSQI. Nineteen individuals with higher baseline PSQI had no significant changes in PSQI or SE post-PR; however, daytime sleep dysfunction was significantly improved after PR. There were no changes in depression or anxiety after PR.

Conclusions

The study findings indicate that participating in PR did not improve SE among patients with moderate or severe COPD, which contradicts prior studies that reported subjective SE improvements after PR. Nevertheless, a significant improvement in objective SE, which was measured by actigraphy, was observed in a subset of patients with lower baseline SE; however, subjective sleep quality was unchanged after PR in this subset.

Additional studies are needed to understand and characterize sleep disturbances in COPD and the benefits of non-pharmacologic interventions and medications.

Written by

Tarun Sai Lomte

Tarun is a writer based in Hyderabad, India. He has a Master’s degree in Biotechnology from the University of Hyderabad and is enthusiastic about scientific research. He enjoys reading research papers and literature reviews and is passionate about writing.