The moods of Alaskans will likely plunge faster over the next few weeks than at any other time during the year — with one day soon poised to wallop each of us with the sorriest attitude of 2011, says a new study that compared the emotional content of 509 million Twitter posts against date, time and geographic location.
Take solace: It's not your fault. All of us high-latitude denizens can now officially blame the seasonal, daylight-swallowing tilt of the Earth for our crankiness, according to an analysis published this week in the journal of Science.
Messages tweeted by millions of people in scores of countries showed that the relative day-to-day change in the amount of potential sunlight has an outsized influence on a person's "positive affect" — depressing it during accelerating fall darkness and boosting with the lights swift return in spring.
It's not so much total amount of light or darkness that counts, says lead author Scott Golder, a sociologist and graduate student at Cornell University. It's how fast the day length changes from one 24-hour period to the next.
"The theory our results support predicts that the highest fluctuations in average (positive attitude) occurs in northern latitudes around the spring (rising) and fall (falling) relative daylength," Golder explained in an email to Alaska Dispatch.
"Today, for example, at approximately (minus) 5.66 minutes in Anchorage, would be predicted to be one of the lowest average (positive attitude) days of the year."
The study — "Diurnal and Seasonal Mood Vary with Work, Sleep, and Daylength Across Diverse Cultures" — analyzed public tweets from 2.4 million users in 84 countries collected across the world between February, 2008 and January, 2010. Alaska was one of the locales cited.
Golder and his advisor, Cornell sociologist Michael Macy, gathered the 140-character-or-less messages from all hours of the day and night — from a wide spectrum of cultures and religions — producing a remarkable index to how people were feeling as they woke up, grappled with the stress of the workday and their ingrained diurnal rhythms, and then relaxed on evenings or weekends. The scientists then charted the results against dates, latitude, sleep schedules, time of day and day of week.
We twitter happiest once we've had our coffee
One conclusion? Deep within our primal, hard-wired neural-circadian, sleep-wake machinery, we're basically all morning persons whose bright attitude and chirpy demeanor wanes as the day unfolds, dipping lower and lower before we finally perk up in the evening. It's not just the grind of work — a similar pattern occurred on weekends, though people didn't fall in mood as much.
"People across the globe display similar rhythms to their moods despite very different cultures, geographies and religions," the authors explained in a summary provided by Science magazine. "According to their analysis, people tend to be more positive on weekends and early in the morning.
"In general, individuals awaken in a good mood that slowly deteriorates as the day progresses."
The study, based in Macy's Social Dynamics Laboratory, is part of a growing trend to use social media like Twitter as a window into human behavior and psyche. Twitter allows users to post short, time-stamped messages on the fly, from almost any place at any time, sometimes giving their friends and followers a streaming feedback to what they're thinking or feeling.
Taken as a whole, this global babble creates an extraordinary archive of human demeanor arrayed by time, date and place. In sense, it's as though the entire world is perpetually filling out a survey – producing a vast trove of data, if you're a social scientist.
"Data from increasingly popular online social media allow social scientists to study individual behavior in real time in a way that is both fine-grained and massively global in scale, making it possible to obtain precise real-time measurements across large and diverse populations," the authors wrote.
They likened Twitter to "a mood ring for the world."
The world's mood ring
In the study, Golder and Macy collected between 25 to 400 individual Tweets from 2.4 million people in 84 identifiable countries — more than half a billiion blurbs about everything from the world politics to personal digestion. They used a linguistic program that analyzed the messages for words that might signal one of 64 different psychological and behavioral characteristics.
"Positive affect" would be indicated by words showing things like "enthusiasm, delight, activeness and alertness." The opposite — "negative affect" — would be suggested by content showing "distress, fear, anger, guilt and disgust."
"Golder and Macy discovered two daily peaks in which tweets represented a positive attitude — relatively early in the morning and again near midnight, suggesting mood may be shaped by work-related stress," according to a story about the work posted by Cornell University.
"Positive tweets were also more abundant on Saturdays and Sundays, with the morning peaks occurring about two hours later in the day. This implies people awaken later on weekends."
Although the same patterns appeared in different cultures and countries, they shifted in synch with differences in habits and schedules. In the United Arab Emirates, for instance, the traditional workweek runs Sunday through Thursday instead of Monday through Friday. As a result, the weekend surge in positive tweets shifted with UAR's work habits — to Fridays and Saturdays.
"That the shape of the affective cycle was similar on weekends and weekdays points to sleep and the biological clock as important determinants of affect, regardless of variations in environmental stress," the authors wrote.
Negative attitudes didn't vary as much as the positive ones, the authors cautioned, with the exception that moods didn't drop quite as much on weekends as during the weekdays.
Maybe people just get cranky when they haven't had their afternoon naps.
"(Negative affect) was lowest in the morning and rose throughout the day to a nighttime peak; this pattern also suggests that people may be emotionally 'refreshed' by sleep," the authors wrote. "The pattern also supports the assumption that (positive affect) and (negative affect) vary independently and are not opposite ends of a single dimension.
"NA is neither the mirror image of PA, nor do the two measures move consistently in parallel."
Moods shifted depending on how fast day changed
One of the most intriguing results showed that moods varied in response to the speed that daylight was increasing or decreasing — not in response to the total amount of daylight.
"Clinical research has found higher prevalence of depressive anxiety during winter at more northern latitudes," they wrote. "Although this was originally attributed to insufficient exposure to light, more recent research on seasonal mood variation supports the 'phase-shift hypothesis,' which points to the importance of the timing of the dawn signal to synchronize the circadian pacemaker."
The authors charted 14.3 million responses against changes in the day-to-day length of possible sunlight, from six minutes gained during the fastest brightening spring days to about six minutes lost during the rapidly dimming days of fall.
"We found no effect of absolute daylength on either PA or NA," they wrote. "However, as predicted by the phase-shift hypothesis, we observed a change in affect with relative daylength."
Alaskans, then, would probably be among the world's citizens experiencing some of the biggest swings in attitude — down when the darkness swiftly ebbs each in fall, up when the light floods back in spring.
"Of course, in northern latitudes, the long days are very long, and the short days very short," Golder explained in an email. "Places that are at very high (or very low) latitudes like Alaska are also places that have the largest variations in daylength … and are thus most likely to be susceptible to experiencing the shifts in baseline, or average, positive affect."
Contact Doug O'Harra at doug(at)alaskadispatch.com.