The buddy beautiful

Friends can be good for your physical as well as your emotional wellbeing
Baby variety
Friends can improve just about every aspect of our life. Photograph: Corbis

Aristotle defined a friend as "a single soul dwelling in two bodies". Members of Facebook whose "friends" reach triple figures may have a looser definition, but how many friends we have, and how easily we make, maintain and lose them, has a significant impact on our emotional wellbeing.

It's no surprise, then, that friends can improve just about every aspect of our life. Recovery from a major operation? Tick, says a 2009 study in the Journal of the American College of Surgeons, an organisation not known for touchy-feely nonsense. This recovery included, incredibly, a reduction in the level of pain felt by patients with the most friends. Likewise, friends can protect us (a bit) from the aftershocks of bereavement, divorce, even the onset of dementia. They don't even have to be great friends – some of the positive effect is simply down to the company: have a pint with a mate and you're by definition not socially isolated.

Some friendships seem easier than others. "Some need little contact and are low maintenance, but you always pick up with them where you left off," says educational psychologist Karen Majors. "There are friends you're just more comfortable with. Others may be more interesting, but they may be more prickly. Really good friends don't take offence. Friendships can end because they stop being equal. You may take different routes, have different experiences, which make it harder to maintain a friendship."

We first recognise the importance of friends in childhood, when we're not really sure how to make them. "As children, we're attracted to those we perceive to be similar to us," says Majors. "From early on, girls' friendships are about shared intimacy and childhood secrets. But in school friends can turn on you, which can be traumatic. Children practise making and breaking friendships."

While some of us may retain a few childhood friends, the biggest opportunity for friendship comes in higher education. A study of long-term friendships by Purdue University in the US found that friendships formed during college years stayed close 20 years later, if they scored highly in closeness and communication to begin with. These friendships survived great distances and an average of six house moves. "At college [university] you can cultivate close friendships because you're in such close proximity for sustained periods," says Glenn Sparks, Purdue's professor of communication. "These relationships are rare and hard to replicate; they're very unusual outside family relationships. Even when distance, jobs, family tended to pull them apart, these friends would say that once they re-established contact, they didn't miss a beat."

I have a university reunion next year. After speaking to Sparks, it seems I would not be reaping the rewards for the emotional investments I made earlier in life if I didn't go. So I'll be off then.

Today's best video

Today in pictures

More from Relationships