Medical Bulletin 09/December/2025

High blood pressure is one of the world’s most common and dangerous health problems, affecting nearly half of American adults. It quietly damages arteries, raising the risk of heart attacks, stroke, diabetes, and kidney failure. Normally, blood pressure dips while we sleep, guided by the body’s internal clock—our circadian rhythm. But when sleep schedules are irregular, that nightly dip doesn’t happen, pushing blood pressure higher around the clock.

To explore how timing affects heart health, the OHSU researchers monitored 11 middle-aged adults over three weeks. For the first week, participants followed their normal sleep habits. Then, for two weeks, they were asked to keep a fixed bedtime, going to bed at the same time every night while maintaining their usual sleep duration. Throughout the study, scientists recorded daily systolic and diastolic blood pressure readings to track cardiovascular changes.

The results were impressive. During the two-week intervention, average systolic blood pressure dropped by over 4 mmHg and diastolic pressure by 3 mmHg. This improvement was seen even among participants already on medication. According to the American Heart Association, lowering systolic pressure by just 5 mmHg can reduce the risk of major cardiovascular events by up to 10%—making consistent bedtimes a remarkably simple way to protect your heart.

The researchers say this “bedtime regularization” is a low-cost, low-risk lifestyle fix that could complement existing hypertension treatments. Unlike dietary restrictions or expensive medications, it simply requires forming a nightly habit—one that trains your body clock for better heart health.

Their next step is to test the approach in a larger population, but the takeaway is already clear: a predictable bedtime could be one of the easiest, most natural ways to keep blood pressure—and your heart—in check.

REFERENCE: Saurabh S Thosar, Alakananda M Sreeramadas, Megan Jones, Nicole Chaudhary, Cassidy Floyd-Driscoll, Andrew W McHill, Christopher T Minson, Robert Rope, Jonathan S Emens, Steven A Shea, Leandro C Brito, Bedtime regularization as a potential adjunct therapy for hypertension: a proof-of-concept study, SLEEP Advances, Volume 6, Issue 4, 2025, zpaf082, https://doi.org/10.1093/sleepadvances/zpaf082

Sugar Alcohol Sorbitol May Raise Risk of Steatotic Liver Disease Development, Study Finds

The sweet truth may be more bitter than expected. New research from Washington University in St. Louis shows that sorbitol—a common sugar substitute found in “sugar-free” gums, candies, and protein bars—may harm the liver much like fructose, the same sugar long tied to fatty liver disease and metabolic problems.

The study, published in Science Signaling, challenges the long-standing belief that sugar alcohols are harmless alternatives to regular sugar.

Artificial sweeteners such as aspartame, sucralose, and sugar alcohols like sorbitol have long been marketed as “healthier” substitutes that help cut calories or manage blood sugar. But scientists are now discovering that some of these sweeteners may disrupt metabolism in surprising ways. Sorbitol, in particular, is so chemically close to fructose that the liver can easily convert it into the same damaging compound.

Led by Professor Gary Patti, a chemist and biologist at WashU, the research team conducted experiments on zebrafish, a model organism often used for studying human metabolism. They found that enzymes in the gut can naturally convert glucose into sorbitol after meals. If the gut bacteria fail to break it down completely, the remaining sorbitol travels to the liver—where it transforms into fructose-like molecules. The effect mirrors the way high-fructose diets trigger liver fat buildup and inflammation, both early signs of steatotic liver disease (fatty liver).

Interestingly, gut microbiota played a pivotal role. Zebrafish with sorbitol-degrading bacteria could process the compound safely, while those lacking these microbes accumulated excess sorbitol, worsening liver stress. This suggests that a person’s unique gut bacterial balance might determine how their body reacts to certain sweeteners. Patti’s team observed that even low doses of sorbitol, similar to what might be consumed in everyday “low-calorie” foods, could end up being converted into harmful metabolic byproducts.

The findings reinforce a growing message among nutrition scientists: there’s no free lunch when it comes to sugar substitutes. While marketed as harmless, sugar alcohols like sorbitol might quietly strain liver health—especially in people with high sugar intake or gut imbalances.

Future research will dig deeper into how diet, microbiota, and metabolism interact to reveal which “sugar-free” choices are truly safe for long-term health.

REFERENCE: Jackstadt, M. M., et al. (2025). Intestine-derived sorbitol drives steatotic liver disease in the absence of gut bacteria. Science Signaling. doi: 10.1126/scisignal.adt3549. https://www.science.org/doi/10.1126/scisignal.adt3549

Study Links Beer Bellies to Harmful Heart Structure Changes, Especially in Men

It’s not just about how much you weigh—it’s where you carry it that really matters for your heart. New research presented at the Radiological Society of North America (RSNA) reveals that abdominal fat, or “belly fat,” causes more harmful changes in heart structure than overall body weight alone, particularly in men.

While doctors often rely on Body Mass Index (BMI) to assess obesity, this study shows that waist-to-hip ratio (WHR)—a simple measure of abdominal fat—may be a far stronger indicator of heart risk. Abdominal obesity reflects an increase in visceral fat, which surrounds internal organs and interferes with normal heart function. This buildup leads to a damaging pattern known as concentric hypertrophy, where the heart muscle thickens, chamber sizes shrink, and the organ struggles to hold and pump enough blood—setting the stage for heart failure.

To understand this link, researchers from University Medical Center Hamburg-Eppendorf analyzed detailed cardiac MRIs from 2,244 adults aged 46 to 78 with no prior heart disease. The data came from the ongoing Hamburg City Health Study, one of Germany’s largest population-based research projects. They compared obesity measured by BMI with abdominal fat measured by WHR and adjusted for factors like smoking, diabetes, high blood pressure, and cholesterol.

The findings were striking. While general obesity correlated with enlarged heart chambers, abdominal obesity led to thicker heart muscles and smaller inner chambers—a more dangerous combination. These structural changes were especially prominent in men, affecting the right ventricle, which pumps blood to the lungs. Researchers believe this may stem from earlier and more severe abdominal fat accumulation in men or the protective effects of estrogen in women.

Even subtle tissue damage was detected in men with advanced imaging, signaling early stress that might go unnoticed in routine exams.

Lead author Dr. Jennifer Erley says these findings highlight the importance of screening for abdominal fat—not just weight—during health checks. People can easily measure WHR at home by dividing waist circumference by hip circumference; results above 0.90 for men and 0.85 for women suggest increased cardiovascular risk.

In short, it’s not the number on the scale but the size of your waistline that could tell the real story of your heart’s health.

REFERENCE: Jonas H. Lund, M.D., Isabel Molwitz, M.D., Ersin Cavus, M.D., Gerhard B. Adam, M.D., Peter Bannas, M.D., Enver G. Tahir, M.D., and Mathias Meyer M.D.; Radiological Society of North America