FROM OUR MONTH-LONG SERIES, "SWEET DREAMS SWEET HEARTS," FOR NATIONAL HEART HEALTH AWARENESS MONTH
The term heart disease doesn't refer to a single concern but to an umbrella under which a variety of cardiovascular conditions exists.
One of these conditions is especially dangerous and has a distinct relationship with sleep disorders: atherosclerosis.
What is atherosclerosis?
This is the scientific name for the more common term, hardening of the arteries.
When arteries become clogged with fatty deposits—also known as plaques—they begin to harden. These plaques are composed of cholesterol, fatty substances, calcium, waste products from cells and blood clotting agents.
The American Heart Association offers this helpful analogy:
“Sometimes deposits in arteries are compared to a plumbing problem. Think of sludge forming on the inside of pipes. That’s not a perfect comparison because buildups don’t just form on artery walls but inside them.”
As artery walls thicken with this “sludge,” it narrows the passage where blood flows. This slows blood circulation, which ultimately robs our tissue and organ cells of necessary oxygen.
Partial or complete blockage of blood flow in the arteries sounds dangerously unhealthy because it is. Your arteries deliver blood not only to the heart, but to other key organs like your brain and kidneys, as well as the muscles and tissues in your legs.
Atherosclerosis then refers to a number of more familiar problems related to those arteries blocked from delivering blood to specific organs. For instance:
- Coronary heart disease is caused by plaques in the arteries of or delivering to the heart
- Angina is chest pain caused by hardened arteries that serve the heart muscle
- Peripheral artery disease (PAD) is another term for atherosclerosis in the blood vessels in the legs
WHY ARE PLAQUES SO DANGEROUS?
They can break off at any moment, wash into the bloodstream, then get stuck elsewhere. These unpredictable obstacles within our vascular systems are the chief cause of heart attacks or strokes.
Another concern: blood clots can form on the surface of a stationary plaque, further blocking blood circulation in the artery. This is better known as thrombosis: circulation restriction becomes so severe that the tissue in need of blood oxygen begins to literally die without it.
While some hardening of the arteries is a normal outcome of aging, damage to the lining of the artery walls (also known as the endothelium) may also create conditions that allow plaques to form there.
Atherosclerosis is a slow, progressive disease caused by a number of factors, including high blood pressure, smoking, elevated blood cholesterol, and two concerns related to poor sleep: systemic inflammation and oxidative stress.
WHAT IS SYSTEMIC INFLAMMATION?
Inflammation itself relates to immune system activity in the body which is part of the healing process. A little inflammation is normal and even healthy.
When you get a paper cut or stub your toe or scrape your knee, it is the inflammatory process that leaps into action to heal the problem. Once healed, the immune system reverts to its role in the background.
However, when the inflammatory process becomes systemic, this means it is chronic, or ongoing. The body never gets a break from the immune system activity, which can ultimately lead to “new normals” that can actually damage the body and usher in the development or worsening of certain conditions.
WHAT IS OXIDATIVE STRESS?
When your body’s systems become imbalanced due to something like systemic inflammation, oxidative stress is a negative outcome. The organs that are targets of ongoing inflammatory processes suffer damage related to ongoing immune system activity.
For people with cardiovascular concerns, oxidative stress can lead to damaged blood vessels as well as damage to the heart valves and muscle itself.
How are sleep health and atherosclerosis linked?
Atherosclerosis can be the result of sleep disorders and problems such as:
- Insomnia (trouble falling asleep, maintaining sleep, or getting enough sleep)
- Sleep breathing disorders such as obstructive sleep apnea (OSA)
Poor sleep caused by insomnia leads to systemic inflammation and high blood pressure. Over time, these two problems will converge on the cardiovascular system and can result in the development of atherosclerosis.
Also, research in the last year has revealed that people with OSA who have no other heart disease risk factors could still suffer from both hardened arteries and something known as increased endothelial dysfunction.
WHAT IS ENDOTHELIAL DYSFUNCTION?
The walls of arteries are known as the endothelium. When they begin to lose their strength, collect plaques or blood clots, they can no longer function efficiently as delivery systems for oxygen-rich blood.
OSA contributes to endothelial dysfunction because it:
- robs the bloodstream of needed oxygen
- creates systemic inflammation
- leads to increases in blood pressure
- denies the heart the period of rest it needs during sleep, making it work harder, and
- elevates stress hormones in the bloodstream, leading to damage to the entire cardiovascular system over time
There’s also a relationship between artery thickness and OSA severity. Reductions in blood oxygen that are the result of pauses in breathing during sleep (apneas) can lead to plaque buildup, chronic dips in blood oxygen, but oxidative stress and damage to the endothelium over time in those with OSA.
How to measure artery health
You may not realize you have atherosclerosis without a test. The carotid intima-media thickness (IMT) assessment is one such test used to identify cases of atherosclerosis.
In recent research, patients with OSA patients were shown to have higher carotid IMT scores. When researchers measure artery health using this assessment, they identified both problems with the endothelium as well as suspected atherosclerosis.
Use of the carotid IMT has been so effective in predicting OSA that some scientists would like to see it used as a predictor of both the presence and the severity of OSA in patients suspected of having a sleep breathing disorder, even before undergoing sleep studies.
How to prevent hardening of the arteries
To prevent these plaques, a person with even mild OSA must be vigilant about identifying and treating it. OSA is a chronic (long-term) condition without a cure, and failing to treat it is grounds for making it worse.
If you have chronic insomnia (bouts of nightly sleeplessness that have continued most nights over three months’ time), you are best advised to seek advice for identifying its root cause and treating it through cognitive behavioral therapies, sleep hygiene improvements, or other approaches.
Other preventative measures include quitting smoking, treating hypertension (high blood pressure), and eating a heart-healthy diet that helps reduce blood cholesterol and triglycerides.
This is a lot to unpack, so let’s break it down to it’s simplest terms:
When you can’t breathe properly at night as you sleep, it creates a perfect storm of physiological conditions that have a negative impact on artery health. Over time, untreated sleep breathing disorders such as sleep apnea or insomnia (or both) will eventually lead to changes in the structures of the arteries that include the build-up of plaques and stiffness that are characteristic of atherosclerosis.
If you’re at risk for these problems, please take your sleep health seriously and review your other habits (such as smoking, diet, and exercise) to see if there are other ways you can help avert the disaster of stiff arteries.