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Loneliness Is Worse for Your Health Than Smoking and Obesity

Time to bolster those social connections.

It’s well-reported that America has a loneliness epidemic. Even before the COVID-19 pandemic, about half of US adults reported measurable levels of loneliness, according to a 2023 report from the Office of the U.S. Surgeon General (1).

Most people experience loneliness from time to time. A 2020 National Academies of Science, Engineering, and Medicine report revealed that more than one-third of adults 45 or older reported feeling lonely (2). Men appear to be particularly vulnerable. In a 2021 survey, only 27 percent of men said they have 6 close friends—that’s half the number it was 30 years ago. Fifteen percent of the men surveyed said they had no close friendships at all, a fivefold increase since 1990 (3).

Feeling socially disconnected has real—and serious—consequences that can take years off your life. “Having healthy, high-quality relationships is the greatest factor that we know in longevity,” says Molly Maloof, M.D., the founder of Adamo Bioscience, a biotech company focused on increasing love and connection. “Loneliness is worse for your health than smoking, drinking, sedentary behavior, and obesity.”

Loneliness is linked to a host of life-shortening mental health issues like depression, anxiety, and substance abuse (4, 5). It also increases the risk of heart disease by 29 percent and the risk of stroke by 32 percent, according to the Surgeon General’s report. And it increases the risk of dementia by 50 percent—the same risk increase as smoking.

About the Expert

Molly Maloof, M.D., is a healthspan-focused medical doctor and founder of Adamo Bioscience. She taught the course “Live Better Longer: Enhancing Healthspan for Longer Lifespan” at Stanford University.

What Is Loneliness?

“Humans are hardwired for connection,” says Maloof. “When we don’t get it, it triggers evolutionarily determined response patterns that undermine our ability to connect, creating a vicious cycle.”

Loneliness is not the same thing as being socially isolated. You can be surrounded by people, and still feel lonely. The key factor is feeling like you have meaningful connections to the people around you. “Everyone’s supposed to have friends, everyone’s supposed to have a tribe,” says Maloof. “The fact that this is broken down so deeply in our society is a recipe for disaster.”

Loneliness Begets Loneliness

Being or feeling alone can be painful. That’s not just a metaphor: When researchers from the University of California and Purdue University looked at the brain scans of people who feel isolated, they found that areas of the same areas of the brain that respond to physical pain light up (6).

Why? “When we feel safe with people, we get oxytocin,” says Maloof, referring to the feel-good neurotransmitter that can lower stress. If you’re not surrounded by people who make you feel safe, you default to feeling unsafe, which triggers your body to go into a hyperaware state.

“Feeling unsafe creates what’s called mitochondrial allostatic load,” she says. That’s the cumulative amount of stress you can handle before it takes a toll on the body. When you reach this tipping point, your sympathetic nervous system gets stuck in “fight or flight” mode. The result is allostatic overload, which is directly related to declines in mental health and an increased risk for heart disease, diabetes, cancer, and more (7, 8, 9, 10).

Hypersensitivity to danger can also lead to cognitive errors that cause you to misinterpret others’ actions or intentions which—insult, meet injury—can make you more lonely, says Maloof. Researchers say that this is a self-preservation response gone bad and often becomes a vicious cycle, according to a study published in the journal Psychology and Aging in March 2020 (11).

“If you’re going out and trying to make friends after being isolated and alone, you might find yourself hyper-defensive and hypervigilant, which can make it harder for you to make stronger connections,” Maloof says. Say that you’re feeling lonely and you have a bad date. Your brain tells you you’ll be alone forever, so you delete every dating app from your phone—and with it, the chance for a good date on your next swipe.

Combating Loneliness

If you’re feeling socially isolated, how do you reduce your allostatic load and overcome your brain’s natural inclination to make things worse? Maloof offers some fixes:

Recognize what’s going on

Just being aware that this is the way your brain is working can help counter the effects of loneliness, Maloof says. “If you get isolated for a long time, you start to perceive people and the way they treat you as negative.” Knowing this can help you fight back against your brain by challenging beliefs. Instead of assuming that your friend who didn’t respond to your DM hates you, you might think he’s just busy.

Build your IRL community

Spending time with a few people you feel truly connected to can lower cortisol and lower stress, says Maloof, who doesn’t think online connections give the same bang for your buck. “There’s so much happening when you’re in a room with someone,” she says. “The vast majority of our communication is nonverbal. So how are you supposed to do that if you can’t see the person’s body?“

Touch grass

Research published in the journal Scientific Reports found that feelings of overcrowding increase loneliness by almost 40%. By contrast, being able to see or hear signs of nature lowers feelings of loneliness by 28% (12).

1. Our Epidemic of Loneliness and Isolation. (2023) The U.S. Surgeon General’s Advisory on the  Healing Effects of Social Connection and Community
2. National Academies of Sciences, Engineering, and Medicine. 2020. Social Isolation and Loneliness in Older Adults: Opportunities for the Health Care System. Washington, DC: The National Academies Press.
3. The State of American Friendships: Change, Challenges and Loss. (2021). Survey Center on American Life 
4. Owczarek M, et al (2022). How is loneliness related to anxiety and depression: A population-based network analysis in the early lockdown period. 
5. Mills R, et al (2022). Assessing Loneliness among Adults Receiving Outpatient Treatment with Medication for Opioid Use Disorder (MOUD). 
6. Eisenberger NI, et al. (2003) Does rejection hurt? An FMRI study of social exclusion. 
7. Fava GA, et al (2019). Clinical characterization of allostatic overload. 
8. Parker HW, et al. (2022). Allostatic Load and Mortality: A Systematic Review and Meta-Analysis. 
9. Steptoe A, Hackett RA, et al (2014). Disruption of multisystem responses to stress in type 2 diabetes: investigating the dynamics of allostatic load. 
10. Sydney E. Andrzejak, et al (2023). The Role of BMI in Allostatic Load and Risk of Cancer Death
11. Segel-Karpas D, Ayalon L. (2020) Loneliness and hostility in older adults: A cross-lagged model. 
12. Hammoud, R., Tognin, S., Bakolis, I. et al. (2021) Lonely in a crowd: investigating the association between overcrowding and loneliness using smartphone technologies.