June 14, 2011 (Minneapolis) -- Three new studies show that people who are more physically active sleep longer and more deeply than those who are sedentary.
For adults with sleep apnea, a condition that stresses the heart and repeatedly interrupts sleep when breathing briefly slows or stops, an exercise program that combined brisk walking and weight training cut the severity of their disorder by 25% -- as much as some kinds of surgery.
“The most compelling point of the research was that this 25% reduction was achieved without any reduction in body weight,” says study researcher Christopher Kline, PhD, a postdoctoral scholar in the department of psychiatry at the University of Pittsburgh School of Sleep Medicine.
Being overweight is a well-known risk factor for sleep apnea, and previous studies have shown that losing weight may improve the condition.
“For a 25% reduction due to weight loss, you actually need to lose about 10% of your body weight,” Kline says.
For his study participants, who weighed, on average, more than 220 pounds, “They’d have to lose 22 pounds for them to achieve the same benefit that we achieved just through exercise.”
A separate analysis on the same study volunteers found that exercise also improved daytime sleepiness, decreased fatigue, and sharpened thinking compared to a program of light stretching.
“I think studies like this one are very important, because we need as many options for treating sleep apnea as we can get,” says Virend Somers, MD, PhD, a cardiologist and sleep apnea specialist at the Mayo Clinic in Rochester, Minn., who was not involved in the research.
Studies have shown that sleep apnea increases blood pressure. Sleep apnea has also been linked to higher risks for a host of cardiovascular problems, including strokes, heart attacks, heart failure, and fluttering heartbeats called arrhythmias.
“I think it’s a very good strategy because along with treating the sleep apnea, exercise, we know, has a breadth of cardiovascular benefits in terms of mitigating established risk factors. This is particularly important in this population,” Somers says.
Still, Somers notes, this is one of the earliest studies to test this approach. And although the risk to patients who want to copy this exercise program is low, he says more studies are needed to see how durable the improvements may be and whether patients could see even more benefit if they combined exercise with weight loss.
Somers and the study researchers say that because apnea can have such serious health consequences, it would be a mistake for people to think, based on this study, that exercise alone could substitute for medical therapies like continuous positive airway pressure, or CPAP, machines, which completely eliminate apnea.
But it’s a step in the right direction, he says.
Exercise Improves Sleep Apnea
For his studies, one that looked at episodes of sleep apnea and another that assessed quality of life, Kline recruited 43 sedentary adults with moderately severe sleep apnea.
Half were assigned to a 12-week exercise program, while the other half were assigned to a low-intensity stretching program for the same length of time. Those in the exercise group walked briskly for 30 to 40 minutes for four days each week and participated in resistance training on two days. Those in the stretching group met twice each week to do 30 minutes of exercises to increase flexibility.
Before and after the exercise programs, researchers evaluated participants by sleep studies in the lab. They also used questionnaires to assess changes to their mood, fatigue, and daytime functioning. And they tested how quickly study participants could solve problems, think, and remember.
After three months, the number of times that participants stopped breathing at night dropped from an average of 32 to 25 in the exercise group. The stretching group saw their breathing problems worsen, going from about 24 episodes a night to 29.
A separate analysis on the same group, found that exercise also improved daytime sleepiness and decreased fatigue. Study participants also reported that exercise sharpened their thinking and improved other aspects of daytime functioning.
Exercise May Improve Other Facets of Sleep
In another small but intriguing study, researchers asked 12 healthy, young adults to wear sensors that monitor movement while they went about their daily lives for about a week.
Researchers then brought them into a lab where they measured how much and how well they slept.
People who were more physically active during the day had better sleep efficiency, which measures how long a person actually sleeps after they’ve gone to bed.
“The people who do more physical activity during the day, those with the highest energy expenditure, are those who sleep better,” says study researcher Rebecca Robillard, a neuropsychologist and PhD candidate at the Center for Advanced Research in Sleep Medicine at the University of Montreal in Canada.
The study was presented at the 2011 annual meeting of the American Academy of Sleep Medicine and the Sleep Research Society, in Minneapolis.
These studies were presented at a medical conference. The findings should be considered preliminary because they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.