Short answer: loneliness and social isolation are linked to a higher risk of heart disease, stroke, diabetes, depression, cognitive decline and early death. The World Health Organization’s 2025 Commission on Social Connection estimated that loneliness affects about 1 in 6 people worldwide and is linked to more than 871,000 deaths a year. Large research reviews have found that weak social connection raises mortality risk by a similar order of magnitude to well-known risk factors. The good news: social connection is something you can build, in small weekly steps. This article explains what the research actually says, how to read the numbers without panic, and what to do about it.
This article is general information, not medical advice. If you are worried about your health or mood, talk to a doctor. If you are in crisis, call or text 988 in the United States or Canada.
Loneliness and social isolation are not the same thing
The WHO describes loneliness as “the painful feeling that arises from a gap between desired and actual social connections,” and social isolation as “the objective lack of sufficient social connections.” Research usually measures them separately: isolation by counting contacts, living arrangements or group membership; loneliness by asking people how connected they feel. Both show links to health, and they overlap but are not identical. You can be isolated without feeling lonely, or lonely in a crowd. We cover the difference, and what to do about each, in our guide on how to cope with loneliness.
What the 2025 WHO report found
On 30 June 2025, the WHO Commission on Social Connection released its flagship report. According to the WHO news release:
- About 1 in 6 people worldwide is affected by loneliness.
- Loneliness is linked to an estimated 100 deaths every hour, more than 871,000 deaths a year.
- Between 17% and 21% of people aged 13 to 29 reported feeling lonely, with the highest rates among teenagers.
- About 24% of people in low-income countries reported feeling lonely, roughly double the rate in high-income countries (around 11%).
- Loneliness and social isolation “increase the risk of stroke, heart disease, diabetes, cognitive decline, and premature death,” and lonely people are described as twice as likely to get depressed.
The report also stresses the other side: social connection “can reduce inflammation, lower the risk of serious health problems, foster mental health, and prevent early death.”
The U.S. Surgeon General’s 2023 advisory
Two years earlier, in May 2023, the U.S. Surgeon General issued an advisory titled Our Epidemic of Loneliness and Isolation. It called social connection a public health priority, reviewed the evidence linking disconnection to physical and mental illness, laid out a framework for a national strategy to advance social connection, and encouraged individuals to invest in relationships through small, everyday actions such as reaching out to friends and joining community groups.
What the key studies show
Much of what these reports say rests on a set of large research reviews that pool results from many long-term studies. Here are three of the most cited, with figures taken from the published abstracts.
| Study | What it pooled | Main finding |
|---|---|---|
| Holt-Lunstad, Smith & Layton, PLoS Medicine (2010) | 148 studies, 308,849 participants | Stronger social relationships linked to a 50% increased likelihood of survival over the follow-up periods studied |
| Holt-Lunstad et al., Perspectives on Psychological Science (2015) | Studies from 1980 to 2014 on loneliness, isolation and living alone | Increased likelihood of mortality of 29% for social isolation, 26% for loneliness and 32% for living alone, after controlling for possible confounds |
| Valtorta et al., Heart (2016) | 23 papers from 16 long-term datasets in high-income countries | Poor social relationships linked to a 29% increase in risk of coronary heart disease and a 32% increase in risk of stroke |
Social relationships and survival (2010)
In the 2010 PLoS Medicine meta-analysis, Julianne Holt-Lunstad and colleagues combined 148 studies covering more than 300,000 people. People with stronger social relationships had a 50% increased likelihood of survival. The association held across age, sex, initial health status and cause of death, and it was strongest for complex measures of social integration. The authors concluded that the influence of social relationships on mortality risk “is comparable with well-established risk factors for mortality.”
Loneliness, isolation and living alone (2015)
A 2015 follow-up review looked separately at objective isolation, subjective loneliness and living alone. After statistical controls for other factors, the weighted averages corresponded to a 29% (isolation), 26% (loneliness) and 32% (living alone) increased likelihood of mortality. Notably, the authors found no difference between objective and subjective isolation, and social deficits were more predictive of death in samples with an average age under 65, which challenges the idea that this is only an issue for older adults.
Heart disease and stroke (2016)
A 2016 systematic review in the journal Heart examined loneliness and social isolation as risk factors for coronary heart disease and stroke. Pooling longitudinal studies with follow-up periods ranging from 3 to 21 years, it found that poor social relationships were associated with a 29% increase in risk of coronary heart disease and a 32% increase in risk of stroke.
How to read these numbers without panicking
Health statistics about loneliness are often repeated in alarming ways. A few points help keep them in perspective.
“871,000 deaths” is a population estimate, not a count
No one recorded 871,000 death certificates that said “loneliness.” The figure is a modeled estimate of deaths across the global population that are statistically linked to loneliness, based on prevalence data and risk estimates from research. It is a useful way to compare the scale of a problem, not a precise tally.
“29% higher risk” is relative, not absolute
A 29% increase in relative risk means that, in the studies analyzed, the rate of heart disease was about 1.29 times higher among people with poor social relationships than among those with stronger ones. If your baseline risk is low, a relative increase still leaves your absolute risk relatively low. The numbers describe groups, not a prediction for any one person.
Association is not the same as cause
These are observational studies. They show that loneliness and isolation go together with worse health, and many control for factors like age and health status, but they cannot fully prove that loneliness causes illness. Illness can also cause isolation, and other factors, such as income or disability, can affect both. That said, the consistency of findings across many studies, countries and outcomes is why major health bodies now treat social connection as a health priority.
Effects vary by measure
The 2010 review found the association was strongest for complex measures of social integration and weakest for a simple yes-or-no measure of living alone. In other words, how connected you are matters more than whether you happen to live with someone.
It is not just an older-adult issue
Loneliness is often framed as a problem for older people living alone, and it does affect many of them. But the research points more widely. The WHO reported that between 17% and 21% of people aged 13 to 29 felt lonely, with the highest rates among teenagers. The 2015 Holt-Lunstad review found that social deficits were more predictive of death in study samples with an average age under 65. And in the United States, a 2023 Pew Research Center survey found that 8% of adults said they had no close friends at all.
For adults in their twenties, thirties and forties, the typical triggers are life transitions: moving for work, a breakup, becoming a parent, switching to remote work or friends moving away. These are exactly the moments when routines that used to supply social contact disappear, and when it is worth rebuilding them on purpose.
Common myths about loneliness and health
- “Only people who live alone are at risk.” The 2010 review found living alone was one of the weaker measures. Feeling disconnected and having few meaningful ties matter more than household size.
- “If you have lots of contacts, you cannot be lonely.” Loneliness is about the gap between the connection you want and the connection you have. Hundreds of followers do not close that gap if no one knows you well.
- “It is just a feeling, so it cannot affect your body.” Large reviews of long-term studies consistently link loneliness and isolation with physical outcomes such as heart disease and stroke.
- “There is nothing you can do about it.” Connection is built through ordinary, repeated contact. That is slow, but it is within reach for most people.
Why connection might matter for health
Researchers have proposed several reasons why social connection and health might be linked. They are not mutually exclusive, and the evidence for each varies.
- Health behaviors. Friends and family can encourage people to see a doctor, take medication, eat regularly, move more or drink less.
- Stress. Feeling unsupported can keep the body’s stress response switched on for longer, while support can buffer stressful events. The WHO notes that social connection can reduce inflammation.
- Practical help. Someone to drive you to an appointment, notice when you are unwell or check in after surgery makes a real difference.
- Mental health. Loneliness and depression are closely linked, and depression itself affects physical health.
- Meaning and purpose. Belonging to a group can give structure and reasons to stay active.
A small-steps plan to build connection
The research describes risk in populations; what you can control is your own week. You do not need a dramatic change. These steps are deliberately small and build on each other.
| Week | Step | Why it helps |
|---|---|---|
| 1 | One friendly exchange a day with someone in your routine | Low-risk contact that rebuilds the habit |
| 2 | Message two people you have lost touch with | Old ties often restart quickly |
| 3 | Join one recurring group, class or volunteer shift | Repeated contact with the same people |
| 4 | Invite one person to a specific plan at a public place | Moves acquaintances toward friendship |
| Ongoing | Keep the recurring activity and one plan every two weeks | Friendship needs many hours over time |
How many hours does friendship take? Research by Jeffrey Hall suggests roughly 50 hours together to become casual friends, which we turn into a weekly calendar in our article on how long it takes to make a friend. For a fuller plan with scripts, see our guide on how to make friends as an adult, and for options near you, our ranked list of places to meet new people.
Small things that count
- Put your phone away during conversations, one of the everyday steps the WHO suggests.
- Greet a neighbor or check in on a friend who is struggling.
- Volunteer, which combines purpose with regular contact.
- Walk or exercise with someone rather than alone.
- Ask your doctor about local programs if you are older, caring for someone or living with a health condition that makes getting out harder.
When to get help
Talk to a doctor or mental health professional if loneliness comes with persistent low mood, loss of interest, trouble sleeping or eating, increased drinking, or thoughts of self-harm. Loneliness is not a diagnosis, but it can be part of conditions such as depression that are treatable.
If you are in crisis: in the United States, call or text 988 to reach the 988 Suicide & Crisis Lifeline. In Canada, call or text 9-8-8 to reach the 9-8-8 Suicide Crisis Helpline. If you are in immediate danger, call 911.
Meeting new people safely
When you start meeting new people, keep first meetings in public places, tell a friend where you are going, arrange your own way home and leave if you feel uncomfortable.
We are building MeetNow, an app designed around small in-person plans at public places, where the host sets the date, time, seats and who pays and picks who joins. It is live on the web at app.trymeetnow.com, starting in Malta. The Android app is on Google Play; the iPhone app is not in the App Store yet. Learn more on our MeetNow app page.
Want to turn this into an actual plan? MeetNow is a free app for meeting people in person: a host posts a plan at a public place, says who pays (host pays, split, pay your own or free) and picks who joins. It is live on the web and works in your browser, starting in Malta. The Android app is on Google Play; the iPhone app is not in the App Store yet. Open MeetNow and see the plans posted in Malta.
FAQ: health effects of loneliness
What are the health effects of loneliness?
Research links loneliness and social isolation with higher risks of heart disease, stroke, diabetes, depression, anxiety, cognitive decline and early death. A 2016 review in the journal Heart found poor social relationships were associated with a 29% higher risk of coronary heart disease and a 32% higher risk of stroke.
How many deaths are linked to loneliness?
The WHO Commission on Social Connection estimated in 2025 that loneliness is linked to more than 871,000 deaths a year worldwide, about 100 every hour. This is a modeled population estimate of deaths statistically linked to loneliness, not a count of individual cases.
What did the Surgeon General say about loneliness?
In 2023, the U.S. Surgeon General’s advisory “Our Epidemic of Loneliness and Isolation” described social connection as a public health priority, reviewed evidence on its links to physical and mental health, and proposed a framework for a national strategy to advance social connection.
Is loneliness as bad as smoking?
Major reviews have concluded that the influence of social relationships on mortality risk is comparable with well-established risk factors. Direct comparisons with specific habits are rough, so it is more accurate to say that weak social connection is a serious, measurable health risk.
Can you reverse the health effects of loneliness?
Research shows associations rather than fixed outcomes, and the WHO notes that social connection can protect health across the lifespan. Building regular contact with the same people, staying active and seeking help for low mood are sensible steps, ideally alongside advice from your doctor.
