Weight gain and obesity are some of the biggest risk factors for sleep apnea. Weight is uniformly distributed around the body, including in the soft tissues of the throat. This additional weight creates pressure on the neck, which can cause an obstruction to the natural flow of air.
An enlarged neck circumference—over 17 inches in men and 16 inches in women—predisposes people to OSA. Losing weight can help with mild and moderate sleep apnea, but severe apnea requires more involved treatment.
Enlarged tonsils and adenoids are especially common in children and can create an obstruction. For children, surgically removing the tonsils and adenoids can usually fully resolve or significantly improve sleep apnea.
The position of the jaw can also cause an obstruction. For people with an overbite, for example, the jaw is pushed backward during sleep.
Abnormalities of the nose, including a deviated nasal septum, nasal polyps, and the enlargement of the nasal tissue (called turbinate hypertrophy) can all cause nasal-passage obstruction, hence blocking air flow.
Thyroid abnormalities. The thyroid gland produces thyroid hormone that affects metabolism. It can cause muscle and tissue changes. When the hormone levels are too low, the result is a thyroid hormone surge, which causes enlargement in the tongue and surrounding tissues, resulting in a narrowing of the throat area.
Smoking provokes inflammation of the upper airways, which can narrow the air passages. Marijuana, when smoked, also causes airway inflammation and can slow down the respiratory system.
Narcotic pain medication, i.e., opioids, can cause apnea by depressing the respiratory center in the brain, causing the respiratory center to become lazy and making the breath slower and shallower.
Body position while sleeping can also predispose people to an obstruction, especially when sleeping on the back as gravity pushes the tongue and the surrounding tissues backward causing the obstruction.
Birth defects and deformities such as facial, palatal, and cranial abnormalities can cause structural obstruction. Facial abnormalities, as seen in patients with Down syndrome, predisposes them to obstruction.
Alcohol causes relaxation of the throat muscles and tongue, thus causing an obstruction. In addition to creating this physical obstruction, alcohol also slows down the respiratory center in the brain, making people more at risk for episodes of apnea.