According to the research, people start their day happy and then the feeling fades slowly as the day goes on. The pattern holds true regardless if it's a workday or a weekend.
However, according to Twitter trends, the feeling of happiness usually lasts two hours longer during weekends, which is primarily attributed to people's longer sleep cycles during weekends.
The study was first published last September in Science in an article called "Happy in the Morning". The article further suggests that because of social media, scientists have been able to study human behavior better and discover new information which would have been difficult to find through traditional population surveys.