There are many potential causes of sleep apnea that can be explored. Most of these causes are based around something that is causing the airways to be blocked. With the airways blocked, you are not getting enough oxygen, which causes a disruption of sleep because your body "wakes up" to breath. You don't notice it, but because of these disruptions, you are not getting enough sleep, which causes you to feel tired the next day. Here are the top causes of sleep apnea:

1. Being Overweight: There are two ways in which being overweight can cause sleep apnea. First of all, there is extra fat tissue built up along the airways, which can cause the blocking of them. Also, the extra pounds can exert pressure on the airways that lead to them tightening, thus becoming blocked. The only way in which this can be resolved is by resolving the issue of being overweight, especially focusing on losing the fat near the neck. 
2. Abnormal Anatomy: There are some abnormalities in the face or neck that can cause problems with sleep apnea. These abnormalities can include enlarged tonsils, adenoids, or even a large tongue. In severe cases, surgery may be required at a young age since this is often a problem that is seen in children and resolved before they reach adulthood. 
3. Drinking Alcohol: Alcohol relaxes the muscles in the body, which makes the airways more likely to collapse. This can also include other drugs that relax muscles, as well. Alcoholics often deal with this problem, which can be resolved by attending meetings to kick the habit. Consuming large amounts of alcohol every day not only affects the body, but sleep, as well. Not getting enough sleep causes more health issues along the way. 
4. Sleeping on Your Back:  When you sleep on your back, excessive weight is being exerted onto the neck, which can cause the airways to become blocked. When you sleep on your side, there is much less of a chance that you are going to be dealing with this issue. 
5. Lost Muscle Tone with Aging: As we age, muscle tone becomes lost, which is why sleep apnea is common among the elderly. With loss of muscle tone, the airways become more relaxed, which allows them to collapse more easily. This can make certain health issues worse, which is why it is important to attend therapy to help retain muscle tone in the neck once the signs of sleep apnea become present. 

By knowing some of the causes of sleep apnea, you can determine what you need to do in order to reverse the problem. Speaking with a doctor, like those at Billings Clinic, is also important in order to determine what other treatment methods may work best for you and your specific situation.