Nearly 40 million adults in the U.S. have sleep apnea, and more than 30 million of them use a continuous positive airway pressure (CPAP) machine while sleeping. However, the machines tend to be expensive, clunky and uncomfortable — resulting in many users giving up on using them. High blood pressure is often linked with sleep apnea because the brain works harder to regulate blood flow and breathing during sleep. A recent study offers new insight into the underlying mechanisms within the brain contributing to hypertension for those with sleep apnea.