Sleep apnea, left untreated for even a few days, can increase blood sugar and fat levels, stress hormones and blood pressure, according to a new study of sleeping subjects. A report of the study’s findings, published in the August issue of The Journal of Clinical Endocrinology & Metabolism, adds further support for the consistent use of continuous positive airway pressure (CPAP), a machine that increases air pressure in the throat to keep the airway open during sleep.
“This is one of the first studies to show real-time effects of sleep apnea on metabolism during the night,” says Jonathan Jun, M.D., assistant professor of medicine at the Johns Hopkins University School of Medicine and the paper’s senior author.
Obstructive sleep apnea (OSA) affects 20 – 30 percent of adults, according to studies published in the American Journal of Epidemiology and Lancet Respiratory Medicine. It occurs when the upper airway closes off during sleep, temporarily interrupting breathing. While it is known that OSA is associated with risks for diabetes and heart disease, there has been no consensus on whether OSA is a cause of these disorders or just a marker of obesity, which predisposes one to diabetes and heart disease.
Previous metabolic studies in patients with OSA, the Johns Hopkins researchers say, usually collected data while participants were awake, thus obtaining only a snapshot of OSA’s aftermath, not the actual sleep period when OSA occurs.
To better understand how OSA affects metabolism, researchers measured free fatty acids in the blood, glucose, insulin and cortisol (a stress hormone) while participants slept in a sleep laboratory at the Johns Hopkins Bayview Medical Center. Participants’ brain waves, blood oxygen levels, heart rates and breathing, along with eye and leg movements, were also recorded each night of the study.