Social connection and wellbeing: what the evidence can and cannot say

Few health headlines are as striking as the claim that loneliness harms health as much as smoking. It is worth slowing down on that sort of sentence. This note looks at two large public documents on the subject, a report from the World Health Organization (WHO) Commission on Social Connection and an advisory from the US Surgeon General, and separates what they establish from what they only suggest. It is general information, and nothing here replaces a conversation with your own clinician.

Loneliness and isolation are not the same thing

WHO defines social connection as the ways people relate to and interact with others. Loneliness, it says, is the painful feeling that arises from a gap between the social connections you want and the ones you have. Social isolation is the objective lack of enough social connections. The figures below sometimes refer to one and sometimes to the other.

How common it is

In its June 2025 release, WHO said that 1 in 6 people worldwide is affected by loneliness. It reported that between 17 and 21 percent of people aged 13 to 29 said they felt lonely, with the highest rates among teenagers, and that about 24 percent of people in low-income countries reported loneliness, roughly twice the rate in high-income countries. WHO noted that data on social isolation are more limited, but estimated it affects up to 1 in 3 older adults and 1 in 4 adolescents.

The US Surgeon General's advisory, titled Our Epidemic of Loneliness and Isolation, says that approximately half of US adults report experiencing loneliness, with some of the highest rates among young adults.

What is established and what is association

WHO says loneliness is linked to an estimated 871,000 deaths each year, or around 100 an hour, and that loneliness and isolation increase the risk of stroke, heart disease, diabetes, cognitive decline and premature death. It also says people who are lonely are twice as likely to get depressed. The advisory reports that loneliness and social isolation increase the risk of premature death by 26 percent and 29 percent respectively, and compares the mortality impact of being socially disconnected to smoking up to 15 cigarettes a day.

Both bodies use strong language, so the question is how firmly cause is established. The advisory is more careful than its headline. It says there is significant evidence of correlations between social connection and health, and that the evidence also supports a potential causal association: it points to a causal-epidemiology approach, experimental evidence in animals, and randomised trials of interventions, and concludes that together these suggest a likely causal association between social isolation and a variety of poor health outcomes. Population figures like these cannot tell any one person what their own risk is.

The picture is tangled. WHO lists poor health, low income and education, living alone, inadequate community infrastructure and public policies, and digital technologies among the multiple causes of loneliness and isolation. Poor health appears on that list as a cause of loneliness, and elsewhere as a result of it, which is a good reason to prefer words like "linked" and "associated" in this note.

Small practical ideas from these sources

Neither document treats connection as only an individual task; both discuss policy and community spaces. For individuals, they offer modest suggestions:

• WHO mentions simple everyday steps such as reaching out to a friend in need, putting away your phone to be fully present in conversation, greeting a neighbour, joining a local group, or volunteering.
• The advisory suggests making time each day to reach out to a friend or family member, minimising distraction in conversation (for example, not checking your phone during meals), and taking part in social and community groups such as fitness, hobby, religious or community service groups.
• It also suggests serving or supporting others, and cutting back on harmful and excessive social media use and on time in front of screens instead of people.

If walking with someone appeals, walking and how much is enough and exercise and mood cover the activity side. Connection can also be part of coping with pressure, a theme in stress and the body.

When it is more serious

WHO says that if the problem is more serious, finding out about available support and services is important, and it notes that loneliness can lead to anxiety and to thoughts of self-harm or suicide. The advisory suggests seeking help during times of struggle by reaching out to a family member, friend, counsellor, health care provider or the 988 crisis line, and being open with your health care provider about big social changes in your life. For ways to find a therapist, see finding a licensed therapist. In the United States, NIMH says to call or text 988 for emotional distress and to call 911 or go to the nearest emergency room in a life-threatening situation. Elsewhere, contact your local emergency number or crisis line. The wider sleep, stress and support shelf has related notes.

The short version

WHO and the US Surgeon General both link loneliness and isolation to worse physical and mental health, and the Surgeon General's advisory describes evidence for a likely causal role, while also noting that much of the data are correlations. Small steps such as contacting one person a day, putting the phone down in conversation and joining a group are the modest ideas both sources offer. If loneliness is heavy or persistent, talk to a clinician, and anyone in crisis should contact emergency services or a crisis line.