If you are watching computer-generated mayhem in the latest action film or scrolling rapidly on your smartphone, you may start to feel a little off. A dull headache, maybe. Dizziness, or creeping nausea.

No, it is not something you ate. A peculiar side effect of life in the 21st century is something called digital motion sickness, or cybersickness: Experts say many of us can grow woozy while viewing moving digital content, feeling as if we are on a boat in a churning sea.

While getting up on the deck of a ship and looking at the horizon helps you feel better, it’s the opposite with digital motion sickness. You see movement — like the turns and twists shown in a movie or video game car chase — that you do not feel. The result is the same: sensory conflict that can make you feel queasy.

 

Smoking still on the wane in U.S.

Smoking, the leading cause of preventable death in the United States, continued to decline last year, federal health authorities reported, with the share of American adults who smoke dropping to 16.8 percent, down from 17.8 percent in 2013.

Smoking has been one of the brightest public health successes of recent history. Nearly half of all Americans smoked in the 1960s, but a broad push against the habit, starting with the surgeon general’s warning in 1964, helped bring rates down.

But the national numbers mask deep disparities. About 43 percent of less educated Americans smoked in 2014, compared with 5 percent of those with a graduate degree. About a third of Americans insured by Medicaid, the health insurance program for the poor, smoked, compared with 13 percent of Americans with private insurance.

 

Pros and cons of knee surgery

People with knees worn out by arthritis will get more pain relief from joint replacement surgery, but it has more risks and there’s a good chance that less drastic approaches also would help.

That’s the bottom line from the first study to strictly test other treatments against knee replacement, an operation done hundreds of thousands of times a year in the U.S. The results appear in the New England Journal of Medicine.

 

More people take more drugs

A study published this month in the Journal of the American Medical Association found that almost 60 percent of adults in the United States take at least one prescription drug -- up from 51 percent in 2000.

The study also documented a spike in the share of adults using five or more medications. The figure jumped from 8 percent in 2000 to 15 percent in 2012.

Two notable exceptions : Prescription pain medication use remained stable, and the use of sex hormones among women dipped.

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