A new study examines people's emotions 140 characters at a time.
Researchers sifted through more than a half billion tweets in 84 countries over two years and discovered how people's moods were reflected in their postings.
They used a program to search for words that indicated happiness, sadness, anxiety and other emotions and moods.
Optimism is higher in the morning before people go to work and school and fades as the day goes on. It rises again at night as people go out with friends or spend time with family.
The study also found fewer negative feelings were expressed on weekend mornings and changes as the seasons do with more negative feelings expressed in the winter when there are fewer daylight hours.