A new study by scientists at the Centro Nacional de Investigaciones Cardiovasculares (CNIC) has found that the severity of a stroke can depend on the time of day it happens.
The research shows that our body’s internal clock, also known as the circadian rhythm, can affect how the immune system reacts to a stroke—and this may change how much brain damage occurs and how well a person recovers.
A stroke happens when blood flow to part of the brain is blocked. This type of stroke, called an ischemic stroke, is one of the main causes of death and long-term disability around the world. Even though treatments have improved, some people recover well, while others do not. This study helps explain why outcomes can vary so much.
Researchers found that neutrophils, which are immune cells that respond quickly after a stroke, behave differently depending on the time of day. Neutrophils are part of the body’s first line of defense. At certain times, they become more aggressive and cause more inflammation.
The team discovered that during those times, the neutrophils release more web-like structures called neutrophil extracellular traps, or NETs. While NETs help trap harmful germs, too many of them can block small blood vessels in the brain and make stroke damage worse.
When this happens, the brain has a harder time getting the blood it needs. This leads to more serious injury. However, when a stroke happens at a time of day when neutrophils are less active, there is better blood flow, less inflammation, and less brain damage.
The study used both mouse models and data from more than 500 human stroke patients. It found that people who had strokes during certain parts of the day suffered more damage than those who had strokes at other times. This means that the body’s immune response—controlled by its internal clock—plays a big role in how serious a stroke is.
These findings help explain why two patients with similar health conditions and risk factors can have very different stroke outcomes. The immune system’s activity level at the time of stroke may be the key.
The researchers say that these discoveries could lead to new ways of treating strokes. For example, doctors might consider the time of day a stroke happens when deciding how to treat a patient. They may also look for blood markers that show how active the immune system is, helping them choose the best treatment for each person.
The study shows the importance of personalized medicine. Understanding how the immune system changes during the day could help doctors give the right treatment at the right time. In the future, this may help reduce stroke damage and improve recovery for more patients.
If you care about stroke, please read studies that diets high in flavonoids could help reduce stroke risk, and MIND diet could slow down cognitive decline after stroke.
For more health information, please see recent studies about antioxidants that could help reduce the risk of dementia, and tea and coffee may help lower your risk of stroke, dementia.
The study is published in Circulation Research.
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