Excerpt from this article:
In 2010, researchers found that 80% of social media posts were announcements about people’s immediate experiences–Facebook status updates like Joe’s “OMG that is A LOT of snow” are the norm in social feeds. So in 2012, two researchers at Harvard were curious about this and decided to see how self-disclosure affects the brain.
It turns out that talking about our own thoughts and experiences activates the rewards system of the brain, providing that same shot of dopamine we get from sex, food, and exercise. The reward activity in the brain is also much greater when people get to share their thoughts with others.
Simply put, Joe’s wake-up tweet gave his brain pleasure.