There are plenty of obvious ways in which your lifestyle affects your physical and mental health.
For instance, there are “healthy” eating habits that actually aren’t so healthy, and there’s the age-old question of whether or not you’re getting enough sleep.
But there’s a less obvious aspect of your lifestyle that might be impacting your health: loneliness.
INSIDER spoke to two experts about loneliness: Dr. Julianne Holt-Lunstad, a professor of psychology and neuroscience at Brigham Young University, and Dr. Nancy Donovan, a psychiatrist who specialises in geriatrics and neurology at Boston’s Brigham and Women’s Hospital. Both have studied the effects of loneliness extensively and have conducted studies on the subject.
Before delving into the adverse health effects that can be brought on by loneliness, it’s critical to understand the definition of that term. Both Donovan and Holt-Lunstad said there are two different types of loneliness: subjective and objective. Objective loneliness refers to the physical state of being alone or socially isolated. Subjective loneliness, on the other hand, refers to the feeling of being alone – even if you’re not actually alone. It’s an emotional rather than physical state.
“It’s that subjective, distressing feeling of that discrepancy between one’s desired and actual level of social connection,” Holt-Lunstad said.
The studies mentioned below show that there are risks associated with both kinds of loneliness.
Loneliness can increase your risk of an early death.
Holt-Lunstad published two major studies that establish the overall effect of loneliness as a risk factor for premature mortality (death that occurs before the average age of death in a certain population).
Holt-Lunstad’s first study examined the extent to which social relationships and other social indicators, such as size of social network and perceived social support, influence one’s risk for mortality. The analysis – which involved over 300,000 participants – found that scoring low on those indicators of social connection carried a similar risk to smoking up to 15 cigarettes per day, Holt-Lunstad told INSIDER. Participants with stronger relationships were found to have a 50% increased likelihood of survival.
The second study involved 3.4 million participants and focused on subjective loneliness and actual, physical social isolation, and found that both can lead to a 30% increased risk of premature death. Holt-Lunstad said this risk exceeds that of obesity, physical inactivity, and air pollution.
Loneliness can lead to depression.
According to Donovan, loneliness can be a risk factor for developing depression. Evidence of this can be found in a 2006 study that looked at results from two population-based studies of middle-aged to older adults. Both studies found that higher levels of loneliness were associated with more depressive symptoms, and that this association stayed stable throughout one’s lifetime.
Loneliness can trigger inflammation in the body.
Steve Cole, a professor of medicine, psychiatry, and biobehavioral Sciences at UCLA, conducted a study in 2007 that examined how genes are expressed differently in people who feel lonely. More specifically, the study found that a group of genes involved in inflammation – the body’s way of defending itself – are more active in those who feel lonely.
This genetic reaction is one that dates back generations. Our bodies still see loneliness and isolation as the threat it was centuries ago, when being alone could mean being attacked by an animal or another group of people. Inflammation is meant to be a defence mechanism to protect us from infection and injury, but too much of it can lead to serious illness like cancer.
Loneliness might make it harder to interact with others.
Holt-Lunstad told INSIDER that those who report greater loneliness also perceive social situations as more threatening. Although this may seem odd – you would assume that those who are lonely would take advantage of opportunities to form connections – it’s a phenomenon that has roots in evolution.
John Cacioppo, a professor and the founder and director of the Center for Cognitive and Social Neuroscience at the University of Chicago, explained to CityLab that loneliness ups the stakes of social interaction because it motivates you to “repair or replace connections that you feel are threatened or lost,” which in turn makes lonely people a lot more sensitive to social information – good and bad.
Further, he explains that thanks to an evolutionary bias, humans are often scared of connecting with someone who could turn out to be an enemy. Therefore, Cacioppo says a neural mechanism causes those who are lonely to approach social situations with a heavy dose of doubt.
Loneliness increases your risk for heart disease.
Both Donovan and Holt-Lunstad highlighted that loneliness has been linked to serious cardiovascular issues. A 2016 study involving 181,000 adults found that loneliness and social isolation were associated with a 32% increase in risk of stroke and a 29% increase in risk for coronary heart disease.
It makes coping with stress more difficult.
Taking on the stress of everyday life alone might be more damaging to your health than taking it on with the help of others. A 2007 study found that social support may optimise a neurochemical response that provides resilience to stress. Findings from the study also showed that social support may moderate environmental and genetic vulnerabilities to stress.
Further, according to Psychology Today, “lonely individuals report higher levels of perceived stress even when exposed to the same stressors as non-lonely people, and even when they are relaxing.”
Loneliness can mess with your eating habits.
A 2012 study focusing on the association between eating disorders and loneliness found that many characteristics of loneliness relate to multiple different kinds of eating disorders, such as anorexia, bulimia, and binge eating disorder. Therefore, loneliness can be a factor in either weight gain or weight loss.
According to the study, for those who gain weight, it’s often because they use food as a way to numb the feelings of loneliness they’re experiencing.
It might be a sign of Alzheimer’s disease.
A study Donovan conducted that looked at 79 community-dwelling older adults found that those who had higher levels of a protein called amyloid also reported a lack of companionship, as well as more frequent feelings of isolation.
Many scientists believe that amyloid accumulation in the brain is the underlying cause of Alzheimer’s. This theory hypothesizes that the amyloid compound messes with communication between brain cells and eventually kills those cells, therefore leading to the cognitive decline characteristic of Alzheimer’s disease.
Loneliness might make you more susceptible to cold and flu symptoms.
A 2017 study found that those who feel lonely are more prone to feeling cold symptoms. The study exposed 159 people to the common cold virus and then quarantined them in a hotel room for five days.
Not everyone got sick, but among the ones who did, those who reported feeling lonely were close to 39% more likely to report more severe symptoms.
Separately, a 2007 study conducted by both Cacioppo and Cole found that lonely peoples’ immune system focuses on fighting bacteria rather than viruses, meaning that lonely people are more susceptible to viral infections.
It might lead to more unhealthy behaviours.
Holt-Lunstad told INSIDER that having positive relationships in your life can motivate you to engage in healthier behaviours, like eating better, getting enough sleep, exercising, and going to the doctor when needed.
A 2010 study that looked at social ties and their link to health behaviour found that relationships can influence behaviour in both positive and negative ways. The study points out that marriage, for example, is associated with a reduced likelihood to engage in risky behaviours, like smoking, drug use, and excessive drinking. Those who are married have also been found to have lower mortality rates, something the study says is often attributed to healthier habits.
Those who have a roommate, partner, or children were less likely to engage in substance abuse, according to the study, meaning that those who don’t have these relationships in their life may be more likely to turn to this kind of behaviour.