She's your best friend. She's the one you call in emergencies or when you just want to talk about nothing and she's always there. But lately you've both been so busy. When you really think about, perhaps it's been months since you've last been in touch.

It happens all the time. Even the closest friendship can fade into the background when you've got so much going on. You might feel guilty for letting the relationship lapse, but you can lose out on a lot when you don't keep your friends close.

The power of pals
Morton J. Mendelson, a professor in McGill University's psychology department, says there are a lot of benefits to keeping up with your pals. Friendships bring elements of stability, intimacy, emotional security, positive feelings and self-validation, according to a study conducted by Mendelson on the value of friendship.

When you lose contact with a close friend, says Mendelson, you lose the corresponding benefits. To make sure you don't miss out on the joys of good buddies, take note of some of Mendelson's recommendations for keeping friendships strong.

1. Speak up
She's chronically late for every coffee date you have. So much so that lately, when she e-mails about making plans, you aren't replying at all. Bad move, says Mendelson. In maintaining any relationship, Mendelson suggests tackling points of frustration head-on rather than letting them blow over. When something bothers you, talk about it. Don't throw a valuable friendship away without putting some effort in. Friendships, like any relationship, take work. And if you walk away rather than speaking your mind, the only one at fault will be you.

2. Understand your friendship
Not all friends serve the same purpose in your life, says Mendelson. "Maybe you have a tennis friend, and a movie friend and a dinner friend," he says. "Not every friend will provide everything you need." One friend might challenge you intellectually, while another provides emotional solace when things get tough. Both you and you friend can get the most out of the friendship when you understand the functions the relationship fulfills.

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3. Strive for quality, not quantity
It's hard enough to keep up one or two friendships, but when you've got a dozen "best friends," staying close can be exhausting. Mendelson says his study showed that we get more benefits from a few close friendships than many casual ones. Consider which of your friendships fulfill you most and put special care into keeping those relationships alive. Let casual acquaintances be just that -- casual.

4. Treasure the old
Long-standing friendships are often the most beneficial, says Mendelson. Who else can give you parenting tips while referencing the time -- after that fight with your mother -- when you swore that when you were a mother, you'd never...? "There is a comfort level that comes from having a history," says Mendelson. "After lasting so long, it stands to reason that the friendship will be more resilient when problems arise." Friendships come and go, so know that when one withstands the test of time, it's worth hanging on to.

5. Make the time
Yes, your life is packed enough, but you need your friends. They keep you real, keep you sane, remind you of the good and bad times, they remind you of who you are. There will never be enough hours in the day to do all the things you need to, but time for friends is something you need to pencil in. Then you can discuss all of those things you can never get around to with a compassionate pal who can relate to all your troubles and triumphs.

Here are the top 10 reasons you need a best friend.

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