That trend also could reinforce the perception that Netflix looms as a threat to the cable-TV industry.

MSN: Netflix's monthly video streaming tops 1 billion hours

"We really have to fight this threat to our sport, because it has a big image and perception problem, " he said.

BBC: CHOOSE A SPORT

"It enhanced the brain's perception across the board, not only to things that are obviously a threat but also to things that aren't obvious but might be threats, " says Lilianne Mujica-Parodi, an associate professor of biomedical engineering at Stony Brook University in New York and lead author of the article.

WSJ: Why We Sweat When We're Stressed