As revealing as individual tweets can be, what do the tweets of a wider population say about us? Largescale analysis of four years of Twitter content from the UK shows the daily emotional peaks and troughs of a nation: 85 percent of variance in expression can be linked to the time of day, demonstrating the power of our circadian rhythm.

Researchers at the University of Bristol found that people are generally more positive in the morning and tend to engage more in analytical thinking as well as “go get ’em” language relating to power and achievement. As the day wears on, we tend to get less positive and talk turns away from person and towards wider social concerns. This hits a peak around 3 or 4 o’clock in the morning when things get existential.

While the study was not able to define a causal relationships between these factors, it noted the timing of these kinds of tweets and typical brain chemistry at that time of day or night: “F1 (period where people express more positive and analytical thinking) occurs at the time when serotonin activity will be falling and cortisol rapidly rising.”

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0197002