Twenty-something men are working many fewer hours than they did a decade and a half ago, according to a new study, and the biggest reason is that they prefer to play video games.

Men aged 21-30 worked 12% fewer hours in 2015 than they did in 2000, according to the study, published Monday by the National Bureau of Economic Research, and about half the reason is the time they spend gaming.

Why it matters: The results suggest that reduced work for prime-age men is not just or even mostly because they can't find jobs or sufficient hours. It's that, rather than accept what is out there, they choose the contemporary equivalent of hanging out at the pool hall or the race track. In fact, in 2015, roughly 15% of young men worked zero weeks over the year, nearly double the rate in 2000.

Meaning in life: The NBER findings, originally flagged last year, say that the decline in work hours by men 21-30 almost exactly mirrored their time spent on leisure — mostly video gaming. In the New York Times, Jane McGonigal, a video game scholar, suggested that games offer this young cohort something lacking in available jobs — a meaning to life, specifically that "I'm trying to improve this skill, teammates are counting on me, and my online community is relying on me."