Doctors are learning that, like other biological processes in the body, the function of our lungs operates on a cyclical basis that is dictated by our body clocks, otherwise known as the circadian rhythm.
The Breathing Rhythm
In a new study,1 Boris Medarov, MD, of the Long Island Jewish Medical Center in New Hyde Park, New York found that circadian rhythms have a significant effect on lung function, a finding that may help determine the best time of day for exercise, as well the administration of medications and medical procedures for various lung diseases.
Medarov learned that lung function peaks during the late afternoon hours, and is at its lowest at around midday. "Circadian rhythms regulate our biological cycles for sleep, activity level, metabolism, and many other processes through out body's exposure to sunlight and darkness," he explained. "Our study finds that lung function has its own rhythm that may govern how much energy we exert throughout the day and the best times to engage in certain activities."
For the research project encompassing about 5 years, 4,835 people underwent several breathing tests, and were divided into 9 groups based on the time of day that the test was performed. The results of the tests, which measured a person's total air volume and other factors when exhaling, were compared with 9 time intervals. Results show that, collectively, the patients' airway resistance was at its highest—when it is most difficult to breathe—around noon, but reached its minimum—when it's easier to breathe—between 4:00pm and 5:00pm, Medarov found.
Practical Implications
"We often associate the end of the work day with being tired and less motivated for physical exertion; however, lung function seems to be at its best during this time," he said. "As a result, exercising or engaging in other physical activities in the late afternoon may help us to achieve optimal performance." The way the lungs function with respect to our body clocks also has implications for timing the administration of asthma medications and certain pulmonary-based medical procedures, he said.
"Many patients with asthma and chronic obstructive pulmonary disease [COPD] administer bronchodilators around the clock, when they actually may need less treatments and a different regimen that includes administering the medication at midday when their lung function is at its lowest," Medarov explained.
Relaxation techniques or biofeedback may also modify lung function's circadian rhythms, helping to manage a person's low and high lung function throughout the day, he added. But more studies are needed to confirm that, Medarov was quick to add.
Biofeedback is a form of complementary and alternative medicine (CAM) that involves the use of a mind-body technique. Specifically, people use their minds to control certain biological processes in the body, at least to a certain extent. Among other diseases, biofeedback is used as a form of therapy for asthma.2
In reacting to the study, Paul Kvale, MD, president of the American College of Chest Physicians stated: "Circadian rhythms can greatly influence how patients with respiratory conditions respond to certain therapies. By knowing how the respiratory system naturally responds at different times during the day, health care providers can adapt treatments and procedures to better fit patients' individual needs."
1. Medarov BI. Hour-to-hour variation of FEV1/FVC. CHEST 2004. 70th Annual International Scientific Assembly of the American College of Chest Physicians. 2004 Oct 23-28. Seattle, WA.
2. Mayo Foundation for Medical Education and Research. Biofeedback: Using the power of your mind to improve your health. Available at: http://www.mayoclinic.com/invoke.cfm?id=SA00083. Accessed October 28, 2004.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
