Friendships and close family relationships can make our lives feel more fulfilling, but do they impact our physical health as well? Focused research in this area is saying, yes.
Social connection is defined by the CDC as the size and diversity of a person’s social network and roles, and includes the functions of the relationships as well as the positive and negative qualities. According to 2024 CDC data, people with diverse and meaningful social bonds are more likely to live longer and be healthier both mentally and physically. CDC reports that social connectedness is correlated with increased resilience, better stress management, improved quality of sleep, and healthier life habits in general. Additionally, chemicals that are released in the brain and body from physical touch, whether from a handshake, a hug, or something more intimate, are known to increase immunity and lower risk for many chronic health conditions including high blood pressure, cardiovascular disease, depression, and dementia.
A psychologist From Carnegie Mellon University in Pennsylvania studied the relationship between social connections and immunity. In a 2017 study the researchers observed over 200 volunteer participants after giving them nasal drops that contain rhinovirus- a virus that leads to the development of the common cold. Participants were assessed before the experiment to determine that they were healthy at the time and not high risk for any type of complications from a cold, and then again for a period of time after exposure to the virus. The results support a correlation between social support and a person’s ability to fight off a virus without it leading to sickness. Those with stronger and more diverse social connections were significantly less likely to develop a cold after exposure to the virus, and those who did had milder symptoms than participants who were exposed to the virus and lacked positive social support in their lives.
Relationships can bring both costs and benefits to our health. A professor at the Ohio State College of Medicine led studies that evaluated the effects of tension and discord in relationships on physical health. Multiple studies conducted in 2015 and 2005 measured changes in body chemistry before and after marital conflicts. This study revealed a significant increase in stress hormones and inflammatory molecules such as cortisol and tumor necrosis factor in participants who had more volatile and hostile ways of handling conflict. These biological changes lead to delayed healing in the body as well as slower metabolism, insulin resistance, and higher risk for chronic diseases such as obesity, metabolic syndrome, and cardiovascular disease. When the release of these biochemicals is constant and at a more amplified level it leads to the acceleration of any other diseases or conditions in the body as well.
The 2015 study by the Ohio State professor and colleagues included more than 40 married couples and measured biological changes within the body for a 24 hour period before and after discussing a difficult topic. The discussion topics used in the experiment were things known to cause disagreement such as money, in-laws, and communication. Assessments included resting energy expenditure (REE), fat and carbohydrate oxidation, triglycerides, insulin, glucose, interleukin 6, and tumor necrosis factor (TNF). The couples ate a high fat meal during the discussion. The results indicated that the manner in which the couple handled the conflict affected the chemicals that were produced in the body and the way their body processed the meal. Couples who disagreed in a more aggressive way produced higher levels of inflammatory hormones which interfered with normal metabolism. Couples who had hostile behaviors during disagreements and also had a history of a mood disorder, such as depression, had significantly lower REE, and higher triglycerides which increase risk of cardiovascular disease, stroke, and heart attack.
The same professor from Ohio State College of Medicine has led other studies focusing on the biological effects of human interactions including one in 2005 which examined the effects of hostile interactions on wound healing. This study included 42 couples with measurable blister wounds who were assessed after a structured social support interaction and again after a disagreement. The wounds were monitored daily for a period of time after this. Those who handled the disagreement more aggressively had significantly higher blood levels of inflammatory cytokines 24 hours after the disagreement. The wounds healed in the more aggressive couples at a rate of 40 percent slower than those of the couples who disagreed more gently and respectfully. In addition to this the more volatile couples were indicated as higher risk for multiple age-related conditions due to the increased inflammatory hormones in their blood stream.
The absence of social connections is also linked with negative health effects. Data from the CDC from 2024 states that approximately 1 in 3 adults report feelings of loneliness, and 1 in 4 adults feel that they lack social and emotional support. Lack of connection with others that also results in lack of social support is defined by CDC as social isolation. Loneliness is defined as a feeling of disconnection from others, and can occur even in the midst of relationships. People who lack connection to others, or who feel isolated and misunderstood even when in the midst of others, are reported to have increased risk for cardiovascular disease, metabolic disorders such as obesity and type 2 diabetes, depression, anxiety, dementia, suicide, and other self-harming behaviors.
A University of Texas professor in 2011 led a study to evaluate the effects of lack of social connections on physical health. The literature review presented consistent data to support correlation between social isolation with the development and progression of multiple chronic conditions including heart disease, recurrent heart attacks, nervous system disorders, cancer, impaired cancer recovery, and slow wound healing. This study also found evidence to support lack of social support to overproduction of inflammatory cytokines and weakened immunity. The professor remarked in the 2011 article that social isolation of otherwise healthy, well-functioning individuals is known to result in psychological and physical deterioration, which is why isolation was often used through the years as a method of torture for prisoners of war. This study also evaluated the positive effects of healthy and supportive relationships, stating that these types of connections boost immune, endocrine, and cardiovascular function, in addition to improving allostatic load which reflects the aging process in the body.
Positive, healthy relationships benefit our health in many ways. Lack of relationships, or relationships that are full of conflict and instability, are as damaging to our physical health as they are to our mental health. Finding healthy ways to connect with others, whether with family or through a hobby, community group, spiritual organization, or other common interest, are not only a way to find a sense of fulfillment but are a part of living our healthiest lives. This includes setting heathy boundaries and seeking outside (sometimes professional) support for any relationships in our lives that are full of conflict or tension. Research is supporting that laughter with friends, love, and acceptance truly are a form of life-giving medicine.
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