Being socially disconnected from others can have big implications on physical health. A new report that reviewed existing research showed how social isolation and loneliness, specifically, can raise your risk for early death.

A meta-analysis in Nature Human Behaviour looked at 90 existing studies that included more than 2.2 million people. The researchers showed the risk for early death goes up 26% for people who were socially isolated and 14% if they were  lonely. 

Researchers already know there are negative health effects of social isolation and loneliness. A 2020 report found being lonely ups your risk for dementia by 50%. Loneliness could raise the risk for death from all causes, – and it may have a risk level that is could be similar to risks from smoking, obesity, or not getting enough physical activity, the U.S. Centers for Disease Control and Prevention reports. (There are clear mental health disadvantages to being disconnected from others and/or feeling lonely, too.)

But scientists are still trying to understand how loneliness and social isolation affect physical health specifically. They want to know the mechanism behind how they contribute to or cause conditions and diseases, or even death. One study showed loneliness and social isolation are associated with more inflammatory chemicals in our bodies. That could lead to inflammatory conditions that cause death. Our brains could also release hormones under stress that impact our physical health in negative ways too, experts say.

Evidence has shown that loneliness can increase levels of the stress hormone cortisol, which can damage cognitive performance. It can also have a negative effect on the immune system. It can also up your risk for inflammation, vascular problems and heart disease.

Older research pointed to two possible mechanisms that could play a role. Those authors said the way that the social situations activate the cardiovascular system, and how they affect sleep dysfunction, can also be possible ways that social isolation and loneliness lead to physical health problems.