If you want to be friends, you've got to put in the time. And new research attempts to determine exactly how many hours it takes to forge that friendship

In a recent report, University of Kansas professor Jeffrey Hall found it takes around 50 hours of time together to make the leap from being a basic acquaintance with someone to a casual friend.

So, I guess the quickest way to make a new friend is to spend a Red Bull-fueled sleepless weekend together.

Presuming you still get along after that much time together, the next stage is to put in 90 hours together to become more than just casual friends and over 200 hours to consider each other close friends.

"We have to put that time in," Hall says. "You can't snap your fingers and make a friend."

Hall used online surveys and surveys of college freshman about how their friendships progressed to come up with the estimates for the time investment required to make it to different levels of friendship. The report was published in the Journal of Social and Personal Relationships.

He found that college freshmen can quickly transition all the way to the close friend stage. 

"When people transition between stages, they'll double or triple the amount of time they spend with that other person in three weeks' time," he said. "I found freshmen who spent one-third of all waking hours in a month with one good friend."

Of course, the study doesn't address the issue of finding people who you want to spend that much time with and vice versa. 

"You can't make people spend time with you, but you can invite them," Hall said. "If you are interested in a friendship, switch up the context. If you work together, go to lunch or out for a drink. These things signal to people that you are interested in being friends with them."

Like almost everything in life, even friendship is a matter of time. If Hall is right, making a single close friend takes the equivalent of working a full-time job for over a month. Of course, if you try to put all that time in in a single month, you're almost sure to get sick of each other.

So be sure to set aside time in what is likely your already busy schedule for friends. Other research and advice has found time and again that it's worth the investment.

"Maintaining close relationships is the most important work we do in our lives," Hall says. "Most people on their deathbeds agree."