We all know networking is good for your career. In fact, according to network science having a large, open network is the single biggest predictor of career success. It also stands to reason that some degree of connection with your fellow man is a mental health essential too. But did you know that being well connected is key for your physical health too?

That's the takeaway from a short but punchy Medium post by Stanford researcher and author Emma Seppälä. In it she lays out a pile of fascinating research that shows social connection impacts not just your mood and your professional success, but your body as well. Here are a few of the startling findings Seppälä lays out.

1. Having no friends is worse for you than smoking.

It sounds outlandish, but Seppälä insists that, according to one study at least "lack of social connection is a greater detriment to health than obesity, smoking and high blood pressure."

2. Strong connections help you live longer.

Another startling study found that "strong social connection leads to a 50 percent increased chance of longevity."

3. Feeling connected helps you ward off disease.

Feeling that you're part of a community is also apparently a hefty immune system boost, Seppälä says, citing research that "shows that genes impacted by social connection also code for immune function and inflammation." Social connection, therefore, "helps us recover from disease faster."

4. Connected people are less likely to be depressed.

Anyone who has experienced loneliness (so, just about everyone then) will intuitively understand the research findings that prove those who are more connected experience lower rates of depression and anxiety.

5. Connected people are also nicer.

According to the latest science, those who feel connected to others "have higher self-esteem, are more empathic to others, more trusting and cooperative and, as a consequence, others are more open to trusting and cooperating with them." Seppälä notes that creates a sort of positive feedback loop where connected people feel cheerful and chatty and this cheerfulness helps them connect with yet more people.

But wait, I'm kind of a loner.

If you're already a social butterfly this post so far is all good news, but if you're more of a loner, are you doomed to ill health and an early demise? Not at all. Seppälä is at pains to point out that a sense of connection isn't equivalent to having thousands of Facebook friends and endless social engagements. What matters is quality not quantity. It's simple -- if you feel connected, you are.

If you don't, you should perhaps think seriously about remedying the situation (Seppälä promises science-backed tips for getting more connected in upcoming posts). But don't feel alone. Social connection, apparently, is on the decline in the U.S. with Americans telling pollsters they had an average of three close friends in 1985 and only one in 2004. Sadly, a quarter of Americans report they have no one to confide in at all.

What advice would you give those looking to feel more connected?