We get one of these little pings on our smartphones, and we get a little hit of dopamine as well. We get excited. We feel anticipation. As we feel this, we want it more and more. So we spend more and more time looking at our phones.

If I post a selfie, and you like it, it's of little cost to you, but it feels great to me. That becomes addictive, and you see people's narcissism so quickly. I think that's a very dangerous thing for us all to be addicted to.

I'm not a fan of the selfie. I think it's at the heart of the narcissism that social media brings into our lives.

We get one of these little pings on our smartphones, and we get a little hit of dopamine as well. We get excited. We feel anticipation. As we feel this, we want it more and more. So we spend more and more time looking at our phones.

It's funny: I spend time in the book criticizing social media, but I'm also aware that a lot of my success is because of social media. I can broadcast myself and my work to thousands of people that are following me or my friends. I do think that social media can be good for self-promotion.

One of the things that makes a social-media cleanse so difficult is that every time we log on, every notification we get is an addictive substance. It's just like any drug.

Social media has a way of changing your mood. I can see a picture of my ex, and it ruins my day.