Many people take sleep for granted. But for some 12 million to 18 million Americans who have sleep apnea, a good night's sleep is something about which they can only dream.

Sleep apnea is a chronic, potentially serious sleep disorder. For people with the condition, breathing repeatedly stops and starts during sleep, and oxygen levels in the blood drop. If not treated, sleep apnea can lead to serious troubles like hypertension, lung damage and heart problems.

It's bad enough that sleep apnea hampers your quality of life, but it can also damage to your finances when it comes to life and health insurance.

How so? If you have sleep apnea, a life insurance company may decline to cover you. Or, if you do get coverage, you might get charged a higher rate and be limited in the amount of coverage you can secure.

The severity of your sleep apnea will play a role in how much coverage you get. For example, if you have a mild to moderate condition and you're treating it and have no other risk factors, getting coverage shouldn't be an issue and premiums shouldn't be pricey.

If you have sleep apnea and are shopping for insurance, it's probably a good idea to undergo a sleep study. Your life insurer will want to review it. Most likely, your health insurance will cover the cost of the test. If your medical records show that you should have a sleep study done and you haven't done so, some insurance companies may choose not to cover you. The test is important because it reveals respiratory patterns, chest muscle activity, oxygenation and other key information.

The insurance company will take into account factors like how old you were when you were diagnosed with sleep apnea, treatments you're undergoing, your blood pressure, your weight, whether you smoke or not, and any other health problems you have.

As for health insurance, if you have sleep apnea, seek out group coverage. That way, you can avoid underwriting, which is a plus when you have a condition like sleep apnea. If you have to get individual coverage, securing a policy may be more challenging. With a pre-existing condition, the insurer's options include covering you with full benefits right away, but at a higher rate; putting a rider or a limitation of coverage on the sleep apnea for a specified time frame; or simply refusing to cover you.

If you get an answer you don't like, you can appeal it. Talk to your insurance agent and doctor to discuss whether you want to do so. A detailed letter from your doctor on your health could prove effective in persuading the insurance company to move in a more favorable direction. It will help if you can show improvement after treatment, such as a decrease in blood pressure.