Close relationships calm your stress system, nudge you towards healthier habits and help you recover from illness. Their effect on lifespan is as large as many physical risk factors, which is why health authorities now call loneliness a public health issue.
Good evidenceSocial isolation means having few contacts: living alone, rarely seeing people. Loneliness is the painful feeling that your relationships aren't what you need. You can be surrounded by people and still lonely, or alone and content. Both carry health risks.
For most of human history, being cut off from the group was dangerous. Your brain still treats it as a threat: stress hormones rise, sleep gets lighter, blood pressure climbs and the immune system shifts towards inflammation.
Strong relationships do the opposite. They buffer stress, encourage you to see a doctor, eat well and stay active, and give you practical help when you're ill. A sense of purpose (feeling your life has direction and meaning) shows similar protective links.
A few close people you can rely on matter most, but wider circles of friends, neighbours and groups all add support and meaning.
The brain treats isolation as a threat and stays on alert.
More cortisol and adrenaline, lighter sleep, higher blood pressure.
The immune system shifts towards chronic, low-grade inflammation.
Higher risk of heart disease, stroke, dementia, depression and early death.
148 studies, 308,849 people
People with stronger social relationships had 50% higher odds of survival over an average of 7.5 years. The effect was comparable to quitting smoking and bigger than physical inactivity or obesity.
Find on PubMed ↗70 studies, 3.4 million people
Loneliness raised the risk of death by 26%, social isolation by 29% and living alone by 32%.
Find on PubMed ↗23 studies
Poor social relationships were linked to 29% higher risk of heart disease and 32% higher risk of stroke.
Find on PubMed ↗6,985 adults over 50
Those with the lowest sense of purpose had about 2.4 times the death risk of those with the highest.
Find on PubMed ↗276 adults given a cold virus
People with the fewest types of relationships were about 4 times more likely to catch a cold than those with the most varied social lives.
Find on PubMed ↗724 men, then their families
Satisfaction with relationships at age 50 predicted health at 80 better than cholesterol levels did.
Find on PubMed ↗Treat relationships like exercise: small, regular doses work best.
A call, walk or meal with someone you care about. Put it in the calendar.
A class, club, choir, team, faith group or volunteering. Seeing the same faces builds friendship.
Walking groups, running clubs and cooking with others count twice.
Volunteering is linked to better wellbeing and a stronger sense of purpose.
Brief friendly chats with neighbours or shop staff lift mood more than people expect.
Persistent loneliness, low mood or social anxiety are worth raising with a doctor or counsellor.
✕ MythLoneliness is just an older people's problem.
✓ FactSurveys find young adults report some of the highest rates of loneliness.
✕ MythLots of online friends means I'm connected.
✓ FactOnline contact helps when it leads to real conversations, but it doesn't fully replace in-person time.
✕ MythIntroverts don't need social contact.
✓ FactIntroverts may prefer fewer, deeper relationships, but they benefit from connection too.
There's no magic number. A few close relationships you can rely on matter more than a large network.
Pets can ease loneliness and get you out walking and talking to people, though the research is mixed.
Start with regular activities where you'll see the same people each week. Friendships take time and repetition.