according to a bunch of studies that i had to read about for my interpersonal communications course,
being lonely will have a vast range of negative effects on you physically
one of them showed that you'll be sick more often, and have a harder time recovering from sickness and injuries, etc.
i don't remember much but it's an interesting topic :P

Few can, I suspect. Fewer still, with great difficulty, and be happy, but I rather think it’s much easier to live with tenderness.