“Apnea” means “not breathing” in Greek, so this means a person doesn’t breathe successfully while asleep. The disease is commonly called “Obstructive Sleep Apnea” (OSA), because it’s due to obstruction in the throat. People with OSA try to breathe, their chest may struggle, they may make gasping movements, but air doesn’t get into the lungs for at least 10 seconds. There’s also a less common Central Sleep Apnea, due to different diseases (e.g. Heart Failure) in which air passes well, but the brain doesn’t tell the lungs to “breathe”.
The main symptom of OSA is daytime drowsiness. A person may nod off frequently, even just for seconds, which is most dangerous if they’re driving (or piloting a plane). They may wake up without feeling well-rested, perhaps with a morning headache, and may have trouble concentrating. Their mood may change. But they may not even realize that they don’t sleep well!
Snoring is not as relevant as people think. Absolutely 100% of people with OSA snore, but so do 50% of adults on earth. If a person doesn’t snore, they don’t have OSA. But if they do snore, even loudly or whatever, it doesn’t help make a diagnosis. All that matters is if they can’t breathe normally during sleep, as described above.
But we don’t ask a patient that, not even if they “think they snore,” because there’s no way at all they can tell — they’re asleep! If they’re aware of what they’re doing, they’re not asleep! But we certainly ask what bed partners or other observers have noticed: does the person snore, have a restless sleep, toss turn or even flail while asleep, and whether they have frequent interruptions in breathing, as described above.
Also, OSA has nothing to with insomnia. It doesn’t stop a person from falling asleep, & it doesn’t completely wake a person up. Even if a person has severe OSA & “arouses” over & over when they don’t breathe, they don’t remember it. [By the way, I have patients who breathe fine, but say they have “insomnia” because they’re aware of awakening every 90-120 minutes after dreaming in a REM cycle, then go right back to sleep, which is 100% normal].
Most people with OSA are obese, and especially have large, bulky necks. If we look into the throat, past the mouth, tissue seems crowded. But this isn’t true of everyone.
People with OSA have greater risks of various heart diseases. They also have a greater risk of sudden death. Unfortunately, there’s no proof that treatment for OSA prevents this, and some evidence that it may not. But it does help control blood pressure in persons with hypertension who take lots of medications.
Diagnosis is made by a sleep study, called a “polysomnogram” (PSG). This measures & records lots of different events while a person sleeps, but the main ones are 1) how many times a person can’t breathe adequately, or at all, when trying (the “AHI”); and 2) how much oxygen is in the blood (oxygen saturation; “O2 sat”) during sleep. “AHI” stands for “apnea-hypopnea index: how many times a minute there’s complete inability to breathe (apnea), or inadequate ability (hypopnea). There’s a do-it-at-home PSG used mainly to rule-out OSA. If the test seems at all positive, it needs to be confirmed in a sleep lab.
Treatment for OSA is mainly weight loss for obese persons, which may not be as easily achieved as it sounds (especially to healthcare providers who order it cavalierly). So in the meantime, we prescribe a machine to deliver Continuous Positive Airway Pressure (CPAP). This forces air past the obstruction when a sleeping person takes a breath. It’s not a respirator that breathes for you (like patients intubated in the ICU).
The main reason to diagnose and treat OSA is to relieve a person’s symptoms, mainly daytime drowsiness (which can be a huge help, like if it prevents dozing at the wheel). It’s also useful to treat high blood pressure which isn’t improving despite several medications. Unfortunately, I see a number of people without daytime drowsiness who get referred for sleep studies because they complain of “insomnia” (or worse, just because they snore). Some degree of OSA gets identified, usually by a high AHI, so they get put on CPAP, which they try & commonly quit.
Actually, in terms of sleep studies, the O2 saturation is much more important than the AHI. Anyone who keeps that above 90% throughout the night is doing very well.