A major new discovery about loneliness reveals that it’s not merely an unpleasant emotional state, it can actually kill you. A meta-analyses of two large studies involving millions of participants found that people who are lonely or socially isolated tend to die a lot earlier than those who don’t suffer from these afflictions, and the different was absolutely huge.

The first study used in the analysis involved 3 million participants, and researchers found that those with a greater social connection had a 50 percent reduced risk of an early death. The second study, which involved 3.4 million individuals, also found the loneliness had a great impact on untimely deaths.

Scientists at Brigham Young University believe that this shows the importance of social connection for human beings, and the findings are worrying because tens of millions of older adults in the United States suffer from social isolation, making this a potential public health crisis.

One reason loneliness may cause an early death is how it impacts day to day lives. A King’s College London study in May found that loneliness in young adults is linked to poor sleep quality, which can in turn lead to health problems down the road.

“The study authors suggest a number of biological processes which may explain the association between loneliness and sleep quality, including a heightened biological stress response,” according to a statement from the college. “Previous research suggests that loneliness is associated with changes in circulating cortisol, indicating elevated activation of the stress response system. Physiological arousal resulting from this process may play a role in the disrupted sleep of lonely individuals.”