If you’re someone who suffers with sleep apnea I’m sure you’re already very aware of the effect it has on your sleep, your partner’s sleep, your levels of concentration and productivity during the day, and literally a thousand and one other things in your life.
In fact, it is extremely well-documented just how dangerous sleep apnea can be for both your mental and physical wellbeing.
If you’re unsure whether you have sleep apnea or are even considered a risk, I suggest you check my article What’s Your Stop Bang Score first (please do come straight back afterwards). If you score 5 or above I have made recommendations for your next steps.
For now, let’s concentrate on the facts about sleep apnea and the heart.
Get Ready for an Overnight Hospital Stay For Official Diagnosis
Before we look in more detail at the effects of sleep apnea on your heart, I just want to discuss the most common form of diagnosis (which should actually start to give you a clue as to what sleep apnea is doing to the heart anyway).
Sleep apnea is a serious condition and occurs either when your breathing becomes extremely shallow or completely stops while you are sleeping.
The amount of time you “stop breathing” is usually somewhere between 10-20 seconds and this can happen a number of times during the night.
Sleep apnea is usually diagnosed via a polysomnography, which is an overnight sleep study.
The study will be conducted by a sleep specialist, either in a clinic or in hospital.
You will have various sensors and electrodes placed on you to monitor and record bodily functions, such as your breathing patterns, blood oxygen levels, brain waves, muscle movements, eye activity, and of course your heart rate.
The results look to confirm how many times per hour you stopped breathing for 10 seconds or longer.
You’re considered to have mild sleep apnea if you had between 5-14 pauses in breath per hour, moderate is 15-29, and severe sleep apnea means that you stopped breathing for 10 seconds or longer a total of 30 or more times an hour.
So, let’s take a look at a case of severe sleep apnea in its mildest form.
Let’s say that you stop breathing for 10 seconds at a time and for a total of 30 times in an hour.
This means that on average, every 2 minutes you breathe stops for 10 seconds. Over the course of 60 minutes you are not breathing at all for 5 minutes.
This means that if you sleep for an average of 8 hours a night you will not be breathing for 40 minutes of this.
Have you ever tried holding your breath for 5 minutes, never mind 40?
Are you starting to understand just how serious sleep apnea is now?
Sleep Apnea and Heart Troubles Infographic
(Infographic courtesy of cardiosmart.org)
How Does Sleep Apnea Affect Heart Rate?
Heart rate can vary widely between individuals during the night. Typically, anywhere between 40-100 beats per minute is considered normal.
It is also true that your own heart rate at night can vary on a daily basis depending on a number of factors including:
- Your levels of hydration.
- How much exercise you took during the day.
- The temperature of your bedroom.
- How elevated you are in your bed.
Your blood pressure will usually drop while you’re asleep because you are generally relaxed. However, it is estimated that in cases of people with sleep apnea their blood pressure will increase by 10%-20%.
You see, when you stop breathing, the amount of oxygen in your blood will drop (and initially your heart rate will drop too).
This automatically sends a message to the brain, which then “tells” the nervous system to signal the blood vessels to tighten and the heart rate to speed up. This will then allow more blood to get to the brain. Phew! There’s quite a lot going on there.
However, this constant nightly exertion can eventually damage the blood vessels that supply blood to the heart. This in turn will ultimately damage the lining of the arteries.
You may be completely unaware that much of this is going on or you may be jolted awake by a sudden snort, or by the fact that you’re gasping for air.
Nevertheless, this whole process will routinely activate the body’s “fight-or-flight” mode because of the amount of stress you’re under.
We are aware that stress (whether consciously or unconsciously) will increase blood pressure, and make the heart beat faster and work harder.
Unfortunately, the story doesn’t end here.
So, your heart rate (and blood pressure) will increase (after the heart rate first drops from the lack of oxygen) when you experience episodes of sleep apnea during the night, but this can then lead to a more permanent problem with your cardiovascular system and heart.
Obstructive sleep apnea can eventually lead to atrial fibrillation, which is a type of irregular heartbeat, or bradycardia (a slow heart rate).
So, you’re telling me that my heart rate dropping and then speeding up because of episodes of sleep apnea can lead to my heart rate eventually slowing down on a more permanent basis?
Correct, you’ve got it.
Bradycardia is actually associated with sleep apnea more often than not, and it can apply to people of ALL ages (just veering of course every so slightly – sleep apnea and bradycardia is commonly referred to apnea of infancy, and is a type of sleep apnea common among babies. I will save this for another article).
The American Heart Association (AHA) defines a slow heart rate (bradycardia) as having a heart rate that beats less than 60 times a minute.
However, this largely depends on your age and physical condition, as a physically active “young” adult is likely to have a resting heart rate of less than 60 beats per minute, but this causes them absolutely no health issues.
With that being said, bradycardia is symptomatic of not getting enough oxygen, and by stopping breathing throughout the night you will not be getting enough oxygen.
Sleep Apnea and Heart Failure
Just those two words alone, heart failure, gives the impression that the heart has failed, it’s no longer working, and there isn’t a thing that can be done about it.
Heart failure actually means that the heart is no longer pumping as well as it should be.
The pumping action of the heart will deliver nutrient-rich blood and oxygen to the body’s cells.
As long as these cells are nourished properly, your body as a whole will function completely normally.
However, in the case of heart failure, the heart is weak and therefore unable to supply the body’s cells with enough blood.
This will manifest itself in you having a shortness of breath, feeling fatigued, and in some cases it may lead to coughing. You will typically find everyday activities including, walking, carrying groceries, or climbing stairs, more and more difficult.
Even though heart failure is a very serious condition, there isn’t actually a cure. The symptoms are generally managed with specific medication and changes in lifestyle (such as losing weight, reducing sodium in your diet, exercising and managing stress), which in many cases will see people leading a perfectly full and enjoyable life.
We have established that the constant tightening of the blood vessels and the speeding up of the heart in order to cope with episodes of sleep apnea will eventually damage the blood vessels and the lining of the arteries.
The damage caused will make it harder for blood to get to the heart, thus meaning the heart will find it more difficult to do its job and ultimately become weaker, i.e. heart failure.
The heart will actually try to compensate for heart failure.
Initially it will stretch to contract more strongly so that it can keep up with the demand for blood, but over time the heart will become enlarged.
The heart will develop more muscle mass because the cells that contract in the heart will get bigger. At first, this means the heart will pump stronger and faster, but this won’t last.
The body will also try to balance things out by narrowing the blood vessels in order to keep blood pressure up, and it will also divert blood away from tissues and organs it considers less important, such as the kidneys.
All-in-all this simply masks the problem of heart failure to begin with until eventually the heart and body can no longer keep up. This is when you will start to notice the symptoms of heart failure.
Can Sleep Apnea Lead to a Heart Attack?
The links between sleep apnea and cardiovascular disease have been studied and well-documented for a number of years.
However, we are now aware that there is a possibility of heart attack, or even death, because of obstructive sleep disorder.
The American Thoracic Society conducted a study in 2007 on 1,123 participants that had been referred for sleep apnea evaluation.
Their progress was followed for the next 4-5 years to see how many of them suffered from various forms of heart disease, such as coronary angiography, bypass surgery, or heart attack, as well as if they died.
The results of the study found that a person with obstructive sleep apnea had a 30% increased risk of having a heart attack or dying over a four or five-year period.
A further study, funded by the National Heart, Lung and Blood Institute, and published in 2013 was in total agreement.
10, 701 people participated in a sleep study for an average of 5.3 years and they were monitored specifically for incidents of sudden cardiac death.
A total of 142 patients died from sudden cardiac death.
The main predictors were being 60 years of age or older, having on average 20+ episodes of sleep apnea per hour, and an oxygen saturation level (when air flows through the lungs) of below 78%.
This study found that the risk of sudden death increased almost twofold. This is particularly true if you stopped breathing more than 20 times an hour, and if your oxygen saturation levels decreased significantly during sleep.
A person who is breathing completely normally will have an oxygen saturation level of 100%. An oxygen saturation level below 88% for any period of time is considered dangerous, and below 85% warrants a hospital visit.
Another fact that came from this study that I found particularly interesting was that someone with sleep apnea has a much higher risk of cardiac death between midnight and 6am.
However, cardiac death occurs more commonly between 6am and noon for people who don’t have sleep apnea.
I have written many articles on this website about sleep apnea and each and every time I wish to drive home just how dangerous this sleep disorder can be.
I don’t do this to scaremonger, cause offense, or to drive people away. I do it in the hope that people will take action against potentially having sleep apnea.
To be completely honest, the number one killer when it comes to sleep apnea is not treating it.
By treating sleep apnea, many of the conditions I have previously discussed can be dramatically improved and even reversed in some cases, and this is true for sleep apnea and the heart.
I mentioned earlier about visiting my article about Stop Bang scores and the next steps to take.
If according to your Stop Bang score it appears that you have severe symptoms of sleep apnea then you MUST make an appointment with your doctor immediately.
You may be told that certain lifestyle changes and natural methods of treatment are all you need (this will very much be down to individual circumstances).
If your symptoms aren’t particularly severe, but there is still a chance you have this life-threatening sleep disorder then I urge you to read my review of Snoring and Sleep Apnea No More.