Somewhere between 5 and 15% of Americans suffer from obstructive sleep apnea (OSA), or frequent episodes of labored breathing and waking up caused by narrowing or closure of the pharynx. These episodes are often accompanied by hypoxia, or low levels of oxygen in the blood, loud snoring, fragmented sleep, and drowsiness during the day. OSA is also a risk factor for several chronic conditions that impact the quality of health, including cardiovascular disease, Type 2 diabetes, and even mild cognitive impairment.
The pharynx narrows during sleep because when we lie down, gravity pulls the tongue backward. To prevent this, a region of the brain called the preBötzinger complex sends signals to hypoglossal motor neurons in the tongue that tell it to contract and remain forward, keeping the airway open. In a new study published in eLIFE, Alfredo Garcia, PhD, and colleagues at the University of Chicago show that a delicate balance of gases that act as signaling molecules in the brain help regulate the activity of motor neurons that activate muscles of the tongue during sleep.