A study reported by Medical News Today last year, for example, suggested that a spouse is 40-70% more likely to meet exercise recommendations if the other spouse does, while another study found that healthy lifestyle changes are more successful with partners.

But perhaps less well recognized are the wide-reaching health benefits of friendships, defined in simple terms as a mutual affection between two or more individuals.

It may not be surprising that friends are good for us, particularly when it comes to mental health; most of us have likely been through some bad times, during which friends were there to offer emotional support and help pull us through.

In fact, research has shown that people with a good support network are at significantly lower risk of depression, with one study reported by MNT last year revealing that in-person contact at least three times weekly almost halved seniors' risk of depression.

But the health benefits of friendships reach much further, as do the health risks associated with lack of companionship.

In this spotlight, we investigate the - perhaps surprising - ways in which friendship is good for us and take a look at why our pals play such an important role in health and well-being.

Your friends could be a stress-buster

Though quite possibly one of the most obvious benefits of friendship, a reduction in stress should not be overlooked.

According to The American Institute of Stress, around 3 in 4 doctors' visits are a result of stress-related illness, and stress is the basic cause of 60% of all human illness and disease.

However, a 2011 study published in the journal Developmental Psychology suggests that simply being around a good friend during a negative experience may reduce stress.

The study, which involved 103 children aged 10-12 years, found that children who spent time with a best friend throughout a negative experience had lower levels of the stress hormone cortisol in their saliva, compared with when negative experiences were endured with a parent, brother, sister, teacher or another individual.

And a new study from the University of California-Berkeley, recently published in the journal Neuropsychopharmacology, suggests that male friendships - often referred to as "bromances" - can reduce stress in bad situations.

To reach their findings, lead author Elizabeth Kirby, of the Department of Integrative Biology at UC-Berkeley, and colleagues housed male rats in the same cage.

Normally, male rats in this situation show aggression toward one another. However, the researchers found that subjecting the rodents to a moderate stressor - 3 hours of acute immobilization - actually caused them to bond.

Compared with the male rats that were housed together in an unstressed environment, those that were subject to the moderate stressor showed an increase in brain levels of oxytocin - known as the "love hormone" - and huddled more.

The team says this indicates that male friendships may alleviate the effects of stressful situations.