They’re bogged down by student loans and rising rents. They’re ditching wedding registries and tiered cakes. They’re running for president.

Welcome to the wide-ranging, complicated world of the generation born between 1981 and 1996: millennials.

All told, this cohort has changed the makeup of America. Millennials have made the country more racially and ethnically diverse, compared with members of Generation X (born between 1965 and 1980), baby boomers (1946 and 1964), the Silent Generation (1928 and 1945), and the Greatest Generation (pre-1928). Millennials take a slower path to traditional household formation, including by delaying or forgoing marriage, or living at home with their parents for longer stretches.

They work more hours each day than prior generations — but they also sleep more. They are more educated than earlier generations. And in their leisure time, they’re more likely to socialize, such as through games, than their older peers.

That’s according to a new study from economist Michelle Freeman at the Bureau of Labor Statistics. Freeman explored how millennials fill their days, and how their choices compare with earlier generations. The study draws on 2017 data from the American Time Use Survey, which produces estimates on how Americans spend their time on an average day. In 2017, millennials were ages 21 to 36, and the nonmillennials were 37 and older.

These habits are of keen interest to researchers, given millennials’ outsized ability — rivaling baby boomers — to recast societal and cultural trend lines. In fact, their economic circumstances and daily habits have often led them to be blamed for “killing” everything, from casual restaurant chains credit cards to the car industry.

Millennials are significantly worse off financially than prior generations, research shows. The net worth of Americans in the 18 to 35 bracket has dropped 34 percent since 1996, according to a May study from Deloitte. Their average net worth was less than $8,000, the Deloitte study found.

Moreover, costs for education have climbed 65 percent in the past decade, and the price of food has risen 26 percent. Add on housing, health care and transportation expenses, and millennials’ behaviors are often less a reflection of their preferences than the result of being strapped for cash.

First, some demographic data: millennials were more likely than older generations to be Hispanic or Latino, Freeman found. Millennials were more evenly split between men and women than their older peers, who were slightly more likely to be female. The cohort was also more likely to be employed and to work full time than nonmillennials.

Freeman told The Post that she was personally surprised by just how much more education millennials had under their belts; 45.3 percent of them had a bachelor’s degree or higher, compared with 35.2 percent of the older age group.

So what do millennials do all day?

They spent more time working, providing child care and taking part in educational activities than their older peers. But they spent less time than nonmillennials on household chores, civic or religious work and leisure activities. That’s largely due to the fact that, compared with older generations, millennials were more likely to be working, taking care of young children or still be enrolled in school, Freeman found.

But they do sleep more. On average, millennials got nine hours of shut-eye each day, compared with 8.6 hours recorded by their older peers.

Millennials spent half as much time each day relaxing and thinking than older generations. Participation rates in sports, exercise and recreational activities were close, with millennials eking out an extra four minutes a day on these pursuits than nonmillennials. Both groups spent the largest share of their free time watching television. But on any given day, millennials were still less likely to watch TV, and when they did, they spent less time doing so.

But there is an upside: Millennials were nearly twice as likely as nonmillennials to play games — from Scrabble to computer games to crossword puzzles — on a typical day, and to spend longer doing so. Older generations, meanwhile, spent more time reading for fun.