Twitter says it can predict how people are feeling based on emotionally tracked phrases.  

The social media company says users are most likely to tweet "feeling sad" on a Sunday in December or a Monday in October, and "feeling happy" on a Tuesday in December or a Tuesday in January. 

"Running late for work" is most common in mid-week in July and Fridays in January.  

Sundays in March, as well as Thursdays and Fridays in November, are the days which see the most Tweets using the word "hangover."