Obstructive sleep apnea occurs when the airway collapses or becomes blocked during sleep. This causes a person to have shallow breathing or pauses in breathing during the night. Not only does this cause drowsiness during the day, but it can increase the likelihood of a whole host of other health problems if left untreated.

How is sleep apnea linked to heart disease?

One of the known risk factors for sleep apnea is high blood pressure. Half of the people with sleep apnea will have high blood pressure. It is also linked to obesity, stroke and heart failure. A recent study published in the journal Circulation: Heart Failure found that when sleep apnea becomes severe, it may cause changes in the heart’s shape and function. These changes are similar to those seen in hypertension, and include increased mass, thickening of the heart wall, and reduced ability to pump.

The good news is that treatment with Continuous Positive Airway Pressure (CPAP), which holds the airway open with a sleep mask to prevent obstruction of the airway, can reverse the negative heart changes. Researchers found that after six months of treatment, and once breathing and sleeping was restored to normal, the heart problems dissipated for people who had only sleep apnea and not other disorders.

                 [SLIDESHOW: 7 Things that Worsen Sleep Apnea]

What about diabetes?

Sleep apnea is also linked to metabolic syndrome and diabetes. One study looked at how sleep apnea may cause metabolic changes that lead to insulin resistance.  Researchers analyzed how intermittent lack of oxygen to the body, also known as hypoxia, affected insulin levels in mice. They used catheters to monitor glucose and insulin sensitivity in mice, and then exposed the mice to either seven hours of oscillated oxygen, with a low of 5 percent once a minute, or a constant rate of oxygen at 10 percent. When compared to controls, researchers found that the intermittent hypoxia associated with sleep apnea caused an increase in insulin resistance.

In addition to insulin resistance, sleep apnea has been shown to affect diabetic peripheral neuropathy, which is nerve damage that can develop throughout the body in people with diabetes. Pain, tingling and numbness can occur, although some people experience no symptoms. A recent study published in the American Journal of Respiratory and Critical Care Medicine found that OSA is linked to DPN in patients with type 2 diabetes, and the severity of sleep apnea is associated with the severity of neuropathy.

Researchers evaluated 234 adults with type 2 diabetes during an overnight sleep study. Participants were monitored with a cardio-respiratory device. They found that the sleep apnea could amplify glucose toxicity in patients with type 2 diabetes, which can cause problems with certain tissue in the body.