About one-quarter of all antibiotics — especially those given for viral colds, chest infections and coughs — are inappropriately prescribed, the University of Michigan Medical School said.

The study, published in the journal the BMJ, looked at the diagnosis codes for more than 19 million privately insured U.S. outpatients in 2016. Viral and bacterial infections sometimes have similar symptoms, but antibiotics are not effective in treating viral infections. Antibiotics promote resistance even when they may be effective against a specific organism. And taking antibiotics when they aren’t needed can mean they won’t be effective when they are.

HRT patch doesn’t raise risk for blood clots

Oral hormone replacement therapy, or HRT, increases the risk for potentially fatal blood clots. But a study in the BMJ found that hormone replacement delivered through the skin entails no increased risk for blood clots. British researchers looked at 80,396 women who had blood clots while on HRT regimens, comparing them with 391,494 controls. They found that oral preparations increased the overall risk of clots by 43 percent. But skin treatments, including patches, creams, gels and under-the-skin injections, had no effect on the risk for blood clots.

Sleeping less than 6 hours tied to heart risk

Sleeping less than six hours a night, and sleeping poorly, are associated with hardening of the arteries, said a study published in the Journal of the American College of Cardiology.

Researchers monitored the sleep of 3,974 healthy men and women, average age 46. They found that compared with people who slept seven to eight hours a night, those who slept less than six hours were 27 percent more likely to be in the highest one-third for the amount of plaque in their arteries. They also found that various blood markers of inflammation were higher in those who got the least sleep. The people who moved the most during sleep also had higher accumulations of plaque than those who slept soundly.