The phenomenon of "decision fatigue" has been found in judges, who are more likely to deny bail at the end of the day than at the beginning. Now researchers have found a parallel effect in physicians: As the day wears on, doctors become increasingly likely to prescribe antibiotics even when they are not indicated.

For the study, published in JAMA Internal Medicine, scientists analyzed diagnoses of acute respiratory infections in 21,867 cases over 18 months in primary care practices in and near Boston.

In two-thirds of the cases, antibiotics were prescribed even though they were not indicated. But whether or not they were indicated, the number of prescriptions increased with time. Overall, compared with the first hour, the probability of a prescription for antibiotics increased 1 percent in the second hour, 14 percent in the third hour and 26 percent in the fourth.

"The radical notion here is that doctors are people, too," said the lead author, Dr. Jeffrey A. Linder, an associate physician at Brigham and Women's Hospital in Boston, "and we may be fatigued and make worse decisions toward the end of our clinic sessions."

An early path to heart disease

Obese children and teenagers already show hints of future cardiovascular problems, new research has found.

German researchers studied 61 overweight and obese children 8 to 21, comparing them with 40 nonobese children of the same age. All were free of disease and not taking any medicines.

Compared with children of normal weight, the obese group had significantly higher triglycerides, higher total cholesterol, lower HDL ("good" cholesterol) and higher LDL ("bad" cholesterol). They also had higher blood pressure, higher fasting glucose and higher fasting insulin readings. Using echocardiograms, the researchers found that in obese children part of the heart muscle — the left ventricle — was thicker on average, which in an adult would be a sign of impending cardiovascular problems. "We do not know if these changes are reversible with weight loss or how they will impact future cardiovascular disease in these subjects," said the lead author, Dr. Norman Mangner, a cardiologist at the University of Leipzig.

The usual advice applies, Mangner said: Follow a healthy diet, maintain a healthy weight and get plenty of exercise.

The study is online in JACC: Cardiovascular Imaging.

Cow's Milk May boost Vitamin D

Many children drink rice, almond or soy milk instead of cow's milk for various reasons — lactose intolerance, allergies, taste preference. But now Canadian researchers have found that children who do not drink cow's milk may have insufficient levels of vitamin D. In a study published online in the Canadian Medical Association Journal, scientists tracked vitamin D blood levels in 2,831 children younger than 6.

About 10 percent of them drank only milk from a source other than cows. The researchers controlled for many factors that can affect vitamin D levels — such as age, sex, weight, vitamin D supplementation, skin pigmentation, and hours of outdoor play. But they still found that children who drank only milk from sources other than cows were almost three times as likely as those who drank only cow's milk to have vitamin D levels below 20 nanograms per milliliter, generally accepted as the lower normal limit for children.