Did you know that stroke is the 2nd leading cause of death worldwide? However, 80% of stroke cases are actually preventable. The biggest risk factor for stroke is high blood pressure, which commonly stems from an unhealthy lifestyle. This may include poor sleeping habits that many people adopt these days. Let’s take a look at how stroke and sleep may be related and how you can reduce your risk of stroke by sleeping better.

What is a stroke?

Stroke is a cerebrovascular disease in which blood vessels in the brain are affected. Stroke can be categorised into ischaemic stroke (about 87%) and haemorrhagic stroke (about 13%). 

• Ischemic stroke - happens when the blood vessels that transport blood, oxygen, and nutrients to the brain are blocked, often by plaques (fat or cholesterol deposits) or blood clots. The brain suffers damage due to the lack of oxygen and nutrients. 
• Hemorrhagic stroke - happens when blood vessels in the brain burst and blood moves out into the brain. 

Some people are at a higher risk of stroke because they have the following risk factors:²

• Hypertension 
• High cholesterol
• Diabetes
• Transient ischemic attacks (TIA) - also known as ‘mini strokes’, in which you may experience symptoms similar to a stroke, but the symptoms last for only several minutes 
• Atrial fibrillation - abnormal heart rates
• Old age
• Lack of physical activity
• Smoking

Symptoms of a stroke

To assess if you are experiencing a stroke, you can use the acronym F.A.S.T.

Face - Facial drooping; usually happens on one side of the face and you may find smiling difficult.

Arms - Weakness or numbness in one arm.

Speech - Slurred speech.

Time - Time is of the essence! Make sure to call the ambulance immediately if you are showing these symptoms. The first hour after stroke onset is known as the ‘golden hour.’ Patients treated promptly within this golden hour tend to see better treatment outcomes and lower death rates and risks for disabilities.¹

Some other symptoms that you should also take a note of include:

• Blurred vision
• Severe headache
• Dizziness
• Difficulty walking and balancing

Is sleep important for minimising the risk of a stroke?

Yes, sufficient and good-quality sleep is important for minimising the risk of a stroke.

There is evidence suggesting sleep deprivation and too much sleep actually increase the risk of hypertension, which is the major risk factor for stroke.² It is recommended for adults to have 7-9 hours of sleep every night to maintain their health and reduce the risk of stroke.

Sleep helps regulate metabolism hormones

The amount of sleep that you get also influences your appetite. Not getting enough sleep signals your body to decrease leptin and increase ghrelin hormone levels, which can lead to increased appetite.²  

Leptin is a hormone produced by your adipose tissues to indicate that you have sufficient energy storage and therefore reduces your appetite. Ghrelin, on the other hand, is a hunger hormone that increases your appetite. Lower leptin and higher ghrelin levels cause greater food intake in people who lack enough sleep.

People who stay up late also have the tendency to consume late-night snacks. This is unhealthy because your body’s metabolic rate is lower during the night, and may not efficiently digest the food that you consume during this time. This can lead to weight gain and higher risks for hypertension and stroke.  

Lack of sleep increases the risk of a stroke

Lack of sleep increases blood pressure and heart rate

Normally, our blood pressure and heart rate lower as we enter sleep at night. However, sleep deprivation can induce an increase in blood pressure and heart rate.³ This was suggested to be due to an increase in the activity of the sympathetic nervous system. 

The sympathetic nervous system is a network of nerves that controls our body’s automatic responses to physical and psychological stress, for example, by increasing our blood pressure and heart rates during ‘fight or flight’ situations. Sleep deprivation may act as a stressor and cause a heightened sympathetic activity that lasts throughout the night and the following day, which in turn leads to a sustained increase in blood pressure.³ 

High blood pressure can cause damage to the blood vessels in long term and make them less elastic and more prone to deposits. The narrowed blood vessels cause blood clots to form which then block the blood flow. This condition is known as atherosclerosis. If the blood flow to the brain is blocked, it can lead to stroke.

Lack of sleep can also activate the inflammatory system and promote the formation of plaques in the blood vessels.³ These can lead to the narrowing of blood vessels and obstruction of blood flow, which increases the risk of stroke. 

Sleep helps with post-stroke recovery

Sleep was suggested to help in post-stroke recovery by facilitating neuroplasticity.⁴

Stroke leads to the death of neurons in brain regions that suffer lack of oxygen. Some stroke patients experience problems in maintaining balance, speech, and memory even after stroke treatment. This may be due to the loss of neurons in the brain regions responsible for these functions. 

Neuroplasticity is a process in which unaffected neurons in the surrounding brain regions reorganise their connections or form new connections with other neurons so that they can compensate for the disrupted functions in the regions affected by stroke.

Watch out for excessive daytime sleepiness

Long-term loss of sleep causes sleep debt, and your body will try to repay it by promoting sleep, even if it is not yet bedtime. If you have been feeling abnormally tired and fall asleep unintentionally during the day, you should take note as this can be a sign of a higher risk of stroke, especially for people with hypertension, obesity, and diabetes.

When to contact a doctor

If you notice the stroke symptoms in yourself or others, you should seek urgent medical attention, especially if you or someone else has risk factors for stroke (e.g. high blood pressure and diabetes). 

Even if the stroke symptoms lasted for a short period of time, it is still important to visit the seek medical attention. This is because you may have had a transient ischemic attack (TIA) which can increase your risk for stroke and require timely treatment. 

Conclusion

Having sufficient good-quality sleep is important to reduce the risk of stroke. This is because sleep duration and sleep quality can influence our metabolism and blood pressure levels which are risk factors for stroke. If you experience stroke symptoms, you should call the ambulance immediately because early treatment increases the chance of survival and reduces the risk of disability following stroke.