Recorded by nurse Bronnie Ware, the book “The Top Five Regrets of the Dying” lists common sorrows of patients on their  deathbed. One of the top regrets the patients said was that they wished they had stayed in touch with their friends.

“Often they would not truly realize the full benefits of old friends until their dying weeks, and it was not always possible to track them down,” Ware wrote. “Many had become so caught up in their own lives that they had let golden friendships slip by over the years. There were many deep regrets about not giving friendships the time and effort that they deserved.”

Friendships play a significant role in promoting overall health, according to the Mayo Clinic. Adults with strong social support have a reduced risk of depression, high blood pressure and stress. Older adults with a rich social life are also likely to live longer than their peers with fewer connections.

University of Missouri — Columbia professor Dr. Gustavo Carlo said these friendships release brain chemicals that foster pleasurable feelings such as reward and happiness. Dr. Carlo, a developmental psychologist at the Department of Human Development and Family Science, studies how children and adolescents learn positive ways of behaving and interacting with one another through quality friend and family relationships.

“Those hormones are things like oxytocin. . . a neurotransmitter that gives us that pleasurable sensation but also draws us closer to other people,” Dr. Carlo said.

Oxytocin, known as the “love hormone,” Dr. Carlo said, is important in instances of human connection. These behaviors include attachment, trust and mother-infant bonding, according to the Society for Endocrinology. Other hormones, such as serotonin and dopamine, provoke rewarding feelings that humans seek out, which is one reason why friendships feel so good. The hormones play a part in arousal, the state of being alert, awake and attentive.

“When you first meet someone, there’s a natural, physiological arousal, and arousal actually reflects stress,” Dr. Carlo said. “Then the question is whether the individual is able to regulate that arousal such that it doesn’t overwhelm them.”

Signs of stress include rapid heart rate, sweaty palms and shortness of breath. These signs often display themselves in unfamiliar social situations or when people first meet each other, according to HelpGuide, an informational mental health and wellness website. Senior Lexi Piecko meets people frequently because of her involvement in Rock Bridge Ambassadors, a club that welcomes new students to RBHS. She said some students show nervousness during the tour.

“When I meet a new student, I kind of have the same questions that I ask each kid,” Piecko said. “I normally ask where they’re from and what they’re interested in, and I look at their teachers and give them my opinions. To make them feel comfortable, I try to talk to them about things they’ll actually care about.”

If people do get overwhelmed, Dr. Carlo said, they might withdraw from interacting with the person they met. Because of this, a timid person might not approach another to be friends. A shy person might feel comfortable with someone who is not necessarily less outgoing but more calm and similar to his or her nature. These people may not talk much and be reserved, but they are unfazed by negative judgment like shy people are.

“This one girl came from a really small school and was super freaked out,” Piecko said. “I walked her around for quite a while and talked to her about how [RBHS is] really not that big and scary.”

Although personality plays a large part in determining friendships, biological features do as well. Individuals can also be attracted to someone and want to form a friendship based on a number of visual cues. Attraction, both platonic and romantic, increases if one individual perceives another to be equally attractive. A Wilfrid Laurier University study on this concept showed research participants tended to sit next to someone they saw as similar to themselves through factors such as race, sex, hair and even glasses. 

In addition, people tend to make connections with others resembling themselves in ways of likes, political affiliations, values and hobbies, University of Missouri — St. Louis Department of Psychological Sciences professor Dr. Bettina Casad said. Similarity is one factor that predicts friendships, dating and marriage, she said.

“People are comfortable with familiarity,” Dr. Casad said. “If someone is similar to us, we can rely on norms, social roles and scripts to interact with them and can expect how social interactions might play out. When interacting with a dissimilar other, people may feel awkward or uncomfortable and not know what to expect or how to act and may worry about acting incorrectly and being embarrassed.”

People might also want to be friends with someone if they consider him or her to be physically attractive, Dr. Casad said. Biology deems features such as large eyes, high eyebrows and larger hips on women attractive. Additionally, attractive male features include broad shoulders, prominent cheekbones and tall height. Facial symmetry is desirable for both genders. 

“We are also attracted to non-biological characteristics including honesty, trustworthiness, pleasant personality [and] humor,” Dr. Casad said. “Supportive of evolutionary theory, women are attracted to . . . ambition, industriousness and earning capacity.”

Alternatively, men most value physical attractiveness, nurture and youthfulness, according to Principles of Social Psychology, a textbook. There are mixed findings on whether men and women equally value attractiveness.

Besides physical appearance, one of the common ways people develop friendship after the first meeting is engaging in prosocial behavior: actions that benefit others, Dr. Carlo said.

“Over time, you continue to have these positive exchanges with one another, compliments and helping each other out,” Dr. Carlo said. “When you develop a friendship with someone, you come to understand that that person is someone you can rely on, that you can trust and that they’re gonna help you when you need help.”

Being able to maintain friendships for a long period of time comes down to a combination of different factors. Physical proximity, sustainable common interests and frequent prosocial behavior are key to sustain healthy relationships. They are more likely to last if people continue to feel like they can rely on each other and have a strong sense of trust. Even at the end of life, friendship continues to play an important role. 

“Having friends is very beneficial to psychological and physical health. Friends provide social support and help us establish our identities and roles within our friendship groups,” Dr. Casad said. “Humans are social animals, and we need others for our well-being and survival.”

What prosocial behavior do you participate in? Let us know in the comments below.