Midazolam is a medicine often given before surgery to help people feel calm and sleepy. It works so well that most people don’t even remember the surgery afterward.
But a new study shows that giving this medicine at night might come with an unexpected risk—it could harm the heart.
Researchers at the University of Colorado Anschutz Medical Campus made this discovery by studying the medical records of over 1.7 million patients who received midazolam before surgery. Among these patients, more than 16,000 showed signs of heart injury after surgery.
When the scientists looked closer, they found something surprising: the risk of heart injury was higher for surgeries done at night. This was especially true for patients who were otherwise healthy.
This led the researchers to ask a big question: why would the time of day make a difference? The answer pointed to a special gene in our bodies called PER2.
PER2 is part of the body’s internal clock, also known as the circadian rhythm. This clock helps control many body functions, including how the heart protects itself. The gene is more active during the day and helps keep the heart healthy.
In lab tests with mice, the researchers found that midazolam may lower PER2 levels at night. That’s a problem because the heart already has less protection during nighttime, and the drug seems to make it worse. Lower PER2 levels mean the heart is more vulnerable to damage.
Midazolam works by increasing the effects of a calming brain chemical called GABA. This helps people relax before surgery. But the study found that this calming effect might also interfere with the heart’s natural defense system—especially at night when the body is already in a lower protection state.
This research highlights something very important: the time of day can change how a drug works in your body. This idea is part of a field called chronomedicine, which looks at how timing affects medicine’s safety and effectiveness.
Doctors already know that some medications, like those for high blood pressure, work better when taken at night. This new study suggests that we may need to think more carefully about when sedatives like midazolam are given—especially during nighttime surgeries for otherwise healthy people.
The study was led by Dr. Tobias Eckle and published in *Frontiers in Cardiovascular Medicine*. It’s a great example of how even small details—like the time of day—can have a big impact on patient safety.
Although midazolam is a common and helpful medicine, this new information may help doctors make better decisions about when to use it. In some cases, changing the timing might help prevent heart problems after surgery.
This research shows how medical science continues to improve. By paying attention to details like timing, doctors can make treatments safer and more effective for everyone.
If you care about heart health, please read studies about a new cause of heart rhythm disorders and eating just one cup of nitrate-rich vegetables daily can reduce heart disease risk.
If you care about heart health, please read studies about blood thinners that may not prevent stroke in people with heartbeat problems and this diabetes drug may protect heart health in older veterans.
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