[by Tamara Sellman RPSGT CCSH for Advanced Cardiovascular Sleep Disorders Center]

---

FROM OUR MONTH-LONG SERIES, "SWEET DREAMS SWEET HEARTS," FOR NATIONAL HEART HEALTH AWARENESS MONTH

---

Often, when we read articles in the newspaper or online, references to “having a stroke” are made in the context of cardiovascular disease.

This could be confusing; after all, isn’t having a stroke something that occurs in the brain? How could it be related to heart disease?

Let’s take apart the relationship between strokes and cardiovascular disease, and while we’re at it, let’s take a closer look at other common ground shared by the two: the matter of untreated sleep disorders.

How are strokes related to heart disease?

Another name for stroke is cerebrovascular accident (CVA). Cerebro- references the brain, while -vascular references the blood vessels.

When a stroke takes place, there's been an interruption in the supply of blood to the brain. Because blood carries oxygen and other critical nutrients like glucose to help keep the brain functional, any delay in the delivery of blood to the brain carries the risk of slowing or halting brain function, as it can’t function without oxygen and glucose.

The longer the depletion of oxygen in the brain, the more likely and severe the damage will be to brain tissues starved of oxygen.

This is why a stroke is considered an urgent medical emergency; early treatment greatly improves one’s chances for survival and minimal damage to the brain.

What are early symptoms of stroke?

Someone having a stroke (or CVA) may experience trouble with:

• Walking
• Speaking
• Comprehension of language spoken to them
• Numbness of the face or limbs
• Paralysis of the face or limbs

Types of stroke

The least common form of stroke is the most deadly one: the hemorrhagic stroke. This occurs when a clot in the brain (an aneurysm) bursts or a weakened blood vessel begins to leak. In either case, the “bleeding out” is difficult to contain and frequently leads to death.  

The more common form of stroke is ischemic stroke. This occurs when a blood vessel that delivers to the brain becomes obstructed by a loose blood clot. This causes the brain to starve of oxygen and glucose.

Finally, a third, stroke-like event is known as a transient ischemic attack (or TIA). Sometimes called “mini strokes,” these happen when blood flow to the brain is disrupted for a short (or transient) period of time (taking place in less than 24 hours before disappearing). This leads to symptoms that mimic those of a stroke.

Stroke is no joke

The following statistics come from the website for the National Stroke Association.

• Each year nearly 800,000 people experience a new or recurrent stroke.
• A stroke happens every 40 seconds.
• Stroke is the fifth leading cause of death in the U.S.
• Every 4 minutes someone dies from stroke.
• Stroke is the leading cause of adult disability in the U.S.
• Up to 80 percent of strokes can be prevented.

Regarding that last statistic: If eight out of ten strokes can be prevented, what are some things we can do to prevent this from happening?

• Managing current cardiovascular issues (atrial fibrillation and high blood pressure) is key.
• Living a heart-healthy lifestyle (quit smoking, lose weight, be physically active, eat a low-sodium diet rich in potassium, drinking in moderation) is also top on the list.
• Treat other conditions (such as sickle cell disease, severe anemia, diabetes, peripheral artery disease) to reduce the risk for blood clots and circulatory system problems.
• If you have a TIA, treat it immediately, and know the warning signs of full-blown strokes so you can tend to them immediately should symptoms arise.
• Pay attention and tend to other measures of health such as blood sugar and cholesterol.
• Finally, get adequate quality sleep. If you struggle with sleep, it might be due to an undetected sleep disorder. Many of them are silent and hard to identify, but in all cases, they are treatable. However, leaving them unidentified and untreated actually raises your risk for having a stroke.

How is stroke connected to untreated sleep problems?

According to a review of literature cited in the International Journal of Stroke, ”Sleep disorders continue to be the most unrecognized modifiable risk factor for stroke.” 

In addition, 

“The relationship between sleep disorders and vascular risk factors and stroke has been well-documented but not fully understood. Sleep disorders may contribute to stroke vascular pathology through multiple direct or indirect mechanisms. In addition, they may also be caused or exacerbated by stroke. Furthermore, the consequences of untreated sleep may impede stroke rehabilitation, lengthen hospital stay, and influence stroke outcomes and stroke recurrence.”

Any time the body is robbed of sleep on a night-to-night basis, this creates stress conditions in the body that lead to systemic problems such as heart disease. Not only are thickened arteries, a weakened heart muscle, and high levels of fatty substances in the bloodstream precursors to the conditions that can lead to stroke, they are the side effects of chronic sleep loss.

Let’s consider all the different ways that untreated sleep disorders can wreak havoc on the cardiovascular system.

SLEEP APNEA

Sleep apnea has a longstanding relationship with obesity, hypertension, and diabetes. Research also shows that the most prominent risk factor for ischemic stroke is hypertension, which can become resistant to therapy if sleep apnea also exists and remains untreated. The worse the sleep apnea, the worse the hypertension and the worse one’s chances of suffering a damaging stroke. (Read more about how sleep apnea stresses the brains of women here.)

SNORING

Snoring may seem harmless enough, but research has shown that loud, habitual (nightly) snoring is, like sleep apnea, an independent risk factors for stroke in middle-aged and older adults. Habitual snoring is also linked to more stroke activity during sleep.

INSOMNIA

Some recent studies show that people who suffer from insomnia are more likely to experience an ischemic stroke due to inflammation and imbalances of stress hormones in the bloodstream, which impact things like blood glucose, cortisol levels, and hypertension. Insomnia by whatever cause should be addressed as it can be symptomatic of other health problems, including hidden sleep apnea.

What may be more surprising: Those who tend to sleep longer (over 9 hours) are also at higher risk for suffering from ischemic stroke, though researchers are still trying to determine why.

SLEEP DEPRIVATION

Sleep deprivation occurs whenever one habitually does not get seven to nine hours of uninterrupted sleep every night. The more sleep deprived one becomes, the more heart problems of all kinds can develop. This is because the heart requires regular rest periods at night to function properly, and ongoing sleep loss leads to things like hypertension, atherosclerosis, atrial fibrillation, and other heart problems linked to stroke.

MOVEMENT DISORDERS OF SLEEP

Less research has been conducted on two common movement disorders related to sleep: Restless legs syndrome (RLS) and periodic limb movement disorder (PLMD). However, some research draws connections between movement disorders of sleep and elevated risks for developing strokes.

While research is scanty on evidence showing that RLS and PLMD could directly cause ischemic strokes, other research shows that both are linked with increased risks for high blood pressure and heart disease, which can then lead to ischemic stroke.  

However, what may be more interesting here is that one’s risk for developing RLS or PLMD has been shown to increase following an ischemic stroke.

CIRCADIAN RHYTHM DISORDERS

Some circadian rhythm sleep disorders are commonly derived from working night or overnight shifts over long periods of time.

One thing that’s already understood about so-called “shift work disorder” is that any kind of activity that disrupts normal circadian rhythm patterns is likely to lead to a number of stroke-related risk factors: higher blood pressure, neurochemical imbalances in the brain and body, obesity, and heart disease.

Probably most convincing in the research are results reported from the Nurses’ Health Study, which found that night shift workers have a four percent higher risk for ischemic stroke for every five years of shift work. For someone who has worked 25 years in night or overnight jobs, that translates into a 20 percent higher risk for suffering a stroke.

Good sleep can help prevent stroke

Striving to get between seven and nine hours of good sleep should be a goal for anyone who is concerned about heart disease or CVAs. Solid sleep, without disruption and which allows for all sleep stages, is critical for maintaining blood pressure, reducing oxidative stress on the heart, and regulating inflammation in the body, three things that are instrumental to stroke prevention. If you suspect you suffer from a sleep disorder, it's in your best interest to be diagnosed and receive proper treatment to reduce your risk factors for stroke.

Sources

“11 Ways to Prevent Stroke.” (March, 2011.) Harvard Heart Letter. Retrieved from the Internet on February 21, 2018.

“Obstructive sleep apnea as a risk factor for stroke and death.” Yaggi HK, Concato J, Kernan WN, Lichtman JH, Brass LM, Mohsenin V. (2005.) New England Journal of Medicine, 353:2034–41. Retrieved from the Internet on February 21, 2018.

“Poststroke restless legs syndrome and lesion location: anatomical considerations.” Lee SJ, Kim JS, Song IU, An JY, Kim YI, Lee KS. (2009.) Movement Disorders, 24:77–84.  Retrieved from the Internet on February 21, 2018.

“Rotating night shift work and the risk of ischemic stroke.” Brown DL, Feskanich D, Sanchez BN, Rexrode KM, Schernhammer ES, Lisabeth LD.  (2009.) American Journal of Epidemiology, 169:1370–7. Retrieved from the Internet on February 21, 2018.

“Severe sleep apnea and risk of ischemic stroke in the elderly.” Munoz R, Duran-Cantolla J, Martinez-Vila E, et al. (2006.) Stroke, 37:2317–21. Retrieved from the Internet on February 21, 2018.

“Sleep Disorders and Stroke.” Wallace, DM, Ramos AR, Rundek F. (2012.) International Journal of Stroke: Official Journal of the International Stroke Society, 7;3:231–242. Retrieved from the Internet on February 21, 2018.

“Sleep-related breathing and sleep-wake disturbances in ischemic stroke.” Hermann DM, Bassetti CL. (2009.) Neurology, 73:1313–1322. Retrieved from the Internet on February 21, 2018.

“Snoring and the risk of ischemic brain infarction.” Palomaki H. (1991.) Stroke, 22:1021–5. Retrieved from the Internet on February 21, 2018.

 “What is Stroke?” (2018.) National Stroke Association. Retrieved from the Internet on February 21, 2018.