Definition of Sleep Apnea
Sleep apnea is a serious sleep disorder where breathing stops and starts during sleep, repeatedly. These interruptions, known as “apneas,” can last from 10 seconds to over a minute and may occur just a few times or even hundreds of times each night. This can lead to poor sleep quality and puts strain on the body. This impacts not only life quality in general but has detrimental consequences for heart health and may lead to strokes and heart attacks. This is a very general definition of sleep apnea, there is a lot more to it. In this article we will dive into details.
But first I would like to share with you a transcription of the interview and the interview itself with one of the leading voices in sleep medicine Prof. Thomas Penzel, who is a Scientific Chair of Sleep Medicine Center at Charité-Universitätsmedizin in Berlin.
Prof. Thomas Penzel: “Sleep apnea is a very common sleep disorder. It is defined as respiratory cessation, no breathing for at least 10 seconds, and this happens during sleep, and it may happen several hundred times per night, so typically in a patient with severe sleep apnea 300 breathing pauses in the night. But sleep apnea often is not so severe, and therefore we have severity criteria.
Everybody has some breathing stops during the night, but typically when dreaming, so a small number of breathing pauses is normal, and therefore we count the number of apnea events per hour of sleep. We say if there are five or less apnea events per hour of sleep, this is normal. Five to 15 breathing pauses per hour of sleep, we say this is mild form of sleep apnea. If there are 15 to 30 apnea events, we say this is moderate sleep apnea, and if there are more than 30 apnea events, then this is severe sleep apnea. Severe sleep apnea may cause arterial hypertension, and it’s a proven risk factor for a myocardial infarction (heart attack) and for stroke, so this is a severe health risk.
One needs to record whether a person is asleep or awake, because it only happens during sleep. One needs to record whether the sleep is still fulfilling its function of deep sleep and dream sleep, or typically be in a patient with sleep apnea, this is lost, so people feel very tired during daytime, and one needs to record the respiration in order to see whether a person is trying to breathe. This sleep disorder is called obstructive sleep apnea, because the loss of breathing is caused by a collapse of earbears.
Typically, we breathe in order to have an exchange of oxygen and CO2, so we inhale oxygen and exhale CO2, and during sleep, this breathing can be less intense, because we are not working and consuming so much oxygen, but in these patients, when they fall asleep, then there’s a collapse of the upper airways, and no air comes in, and no CO2, so this is the problem, this is the disorder.”
Reasons for sleep apnea (phenotypes)
Prof. Thomas Penzel: “There may be different reasons for this obstruction of the upper airways. This is what we call phenotypes. One phenotype is that people have, by genetics, by nature, a short chin, and the short chin makes a small size of the upper airways, and then it is easy for the airways to collapse. Another phenotype is when breathing gets lower during the night, and oxygen drops normally, which is quite normal, then the patient, the subject, does not respond to the lowering of oxygen value.
If oxygen gets lower, one should increase breathing, and if there’s not such a reaction, that is another phenotype. It is a low response to chemo receptor to drop by. Then there’s another phenotype where oxygen gets low, but somehow their muscles, they do not react adequately, so the muscle strength of the breathing muscles is not strong enough. That’s muscle fatigue, another phenotype. And then we have another phenotype, we have altogether four phenotypes at the moment. The fourth phenotype is that the wake-up, the arousal threshold may not be sensitive enough. So if oxygen drops, in order to breathe again, the brain center for respiration needs to coordinate the breathing, so it needs to open the air-pairways. This is the muscle in the human. It’s not stiff, but it is a muscle which we can control for breathing and for speaking, and if this respiratory center is not activated enough, we have a kind of arousal weakness. So this is the fourth phenotype. So until now, we know four different ways how to come to the disorder of obstructive sleep apnea.
Treatments
Q: Is it important to identify this phenotype or the treatment is always the same for everybody regardless the phenotype?
Prof. Thomas Penzel: “Until now, the treatment is CPAP. This works for all phenotypes, but for some phenotypes, this mask needs to be taken every night. It is like glasses. If you use the mask, the airways are open, and it’s a perfect treatment. But to use the mask every night is not so nice for many people. Therefore, people often don’t like to use it. And therefore, other ways of treatment were developed. One type of treatment is a mandibular advancement device. You put it in your mouth, and it’s like this proxisome kind of device you put forward the jaw in order to open the air-pairways. This is good for some phenotypes. It is good for the phenotype with a small jaw.
So, and then there’s another type of treatment, which is a stimulator. It stimulates the breathing muscles. I told you about this weakness of breathing muscles. So this is a treatment predominantly be used for another phenotype. And now very lately, there are new drugs which also have effect on sleep apnea. So they may have an effect on the chemo receptors. So we assume that the new therapeutic possibilities, they are more specific to some phenotypes.
Until now, the overall treatment, which works in everyone is CPAP, but the new treatments may be more specific for some specific phenotypes.”
Q: Is there any way to prevent sleep apnea?
Prof. Thomas Penzel: “One can try to have good training. So in order not to get obese, obesity is a risk factor. So all the usual things which are recommended by any doctor to any patients. – That can help. Healthy lifestyle. Then one has less sleep apnea, but much of it is just genetic predisposition. So with that one cannot do much.”
Q: Will it be possible to diagnose sleep apnea with mobile phones in the future?
Prof. Thomas Penzel: “Yes, we have done a clinical trial with a mobile phone with a French app, which can diagnose sleep apnea. We are also currently doing another study with a company from England, which uses snoring and sound analysis in order to diagnose sleep apnea. So I think that new smartphone-based devices can diagnose to a certain degree. There are some forms of sleep apnea which are more complicated and for which this kind of simple diagnosis does not work. This is not the problem. The problem is who pays for the diagnosis. Does the healthcare system pay for the app for the diagnosis or not? When we put out diagnostic tools, which are easy to use, then we find sleep apnea in 40% of all people. There was a study in Switzerland looking for sleep apnea in people over the age of 40. They found sleep apnea in 70%. Very few people without sleep apnea.”
Link to the study: “Prevalence of sleep apnoea syndrome in the middle to old age general population”
Figure from above mentioned study. “Prevalence of sleep apnoea syndrome in the general population aged 40 years or older”.
Prof. Thomas Penzel: “This means a simple diagnostic device would be positive in almost everyone. So this is the problem of the simple devices. Therefore, healthcare systems, they simply do not pay for it because then they would create everyone a sleep apnea patient. Therefore, there’s a big resistance of healthcare systems to pay for it. Sleep apnea is more than just the finding of breathing process. It is also suffering from the job. To go to the doctor, only a person will really suffer. That is a simple recording in an otherwise healthy person. You will find apneas and they have no relevance. So it’s not about finding apneas, it is the whole picture. And therefore, healthcare systems do not pay simple devices but they pay for devices run by medical people. Then they do reimburse it.”
Mouth taping during CPAP
Q: I interviewed many people with sleep apnea to really understand this disease, their problem. These people really suffer. And this is very touching as well. I was very surprised – some of them who are on the CPAP nose mask, they tape their mouth shut to support the therapy itself. Do you have an opinion on this practice?
Prof. Thomas Penzel: “The mouth needs to be shut in order to have this therapy effectively because the air is blown through the nose and needs to put the upper airways under higher pressure. That’s the effect of CPAP. In order to open the upper airways and then one can breathe on top of this higher pressure level freely through the nose. If the mouth is open, the pressure will immediately go out of the mouth and there’s no effect of CPAP. It is very important to have the mouth closed. Normally when one blows air in the nose, there are reflexes which close the mouth. So normally, normal subjects, they don’t need mouth taping because the reflexes let them close the mouth. If the mouth is not closed automatically, something is wrong with the reflexes. This can be because the pressure was not done correctly or the mask was not done correctly. Most of the cases of patients who need mouth taping, it was not a good application of the CPAP mask. And I would recommend the people go to the sleep lab, let the mask and the pressure be adjusted to fit optimal. Then there’s no need for mouth taping.”
Types of sleep apnea
There are three main types of sleep apnea:
- Obstructive Sleep Apnea (OSA): The most common form, where the throat muscles relax too much, blocking the airway. However each case is different in terms of different muscle groups that take part in apnea event, and the cause may be different for each person (see mentioned in the beginning phenotypes). It should be approached individually.
- Central Sleep Apnea (CSA): This type occurs when the brain fails to send the right signals to the muscles that control breathing. Less common, more difficult to detect.
- Complex or Mixed Sleep Apnea: A combination of both obstructive and central sleep apnea symptoms. Usually CSA occurs first and OSA follows.
Almost 1 billion people have sleep apnea
Please refer to the following famous estimation: “Estimation of the global prevalence and burden of obstructive sleep apnoea“
Why is Sleep Apnea Dangerous?
Untreated sleep apnea can lead to:
- Cardiovascular Issues: Increases the risk of high blood pressure, heart disease, and stroke.
- Diabetes: Disrupted sleep can contribute to insulin resistance.
- Mental Health: Can exacerbate anxiety, depression, and lead to memory problems.
- Daytime Fatigue: Poor sleep quality often causes drowsiness during the day, which can impair focus, productivity, and increase accident risk.
What Causes Sleep Apnea?
Among others, the following factors can contribute to sleep apnea:
- Obesity: Excess weight around the neck can obstruct the airway.
- Age: Sleep apnea becomes more common as we age. 50+ is a risk factor.
- Anatomy: As mentioned before small chins but also large tonsils, or certain jaw structures can increase risk.
- Genetics: A family history of sleep apnea may increase your chances.
- Gender: Men are more likely to develop sleep apnea than women, though the risk increases for women after menopause.
Common Symptoms
Most people with sleep apnea are unaware of their interrupted breathing. However, some common signs include:
- Loud snoring
- Episodes of breathing cessation during sleep (often noticed by a partner)
- Gasping or choking during sleep
- Frequent nighttime awakenings
- Excessive daytime sleepiness
- Morning headaches
- Dry mouth or sore throat upon waking
