Americans’ Sleep Schedules May Be Syncing With Lifestyle Factors Over Natural Sunlight

Americans’ sleep schedules are increasingly less likely to be synced with natural patterns of daylight and more likely to sync with lifestyle factors. That’s the conclusion of a new study that looked at the relationship between Americans’ Twitter usage and “social jet lag.”

“Social jet lag is defined as the difference between when people sleep on free days (when their sleep is mostly set by their biological clock) and work days when they have to be awake at certain times because of their jobs and other obligations,” Michael Rust, Ph.D., study author and principal investigator at the University of Chicago’s Rust Lab, told Mattress Clarity via email. “You can think of it like you are spending the workweek in one time zone and then the weekends in another, which is why we think of it as jet lag.”

The study, which was published in the journal Current Biology, is one of few studies to explore how social pressures — such as work and school schedules — might affect people’s sleep and activity patterns from one day or season to the next. Specifically, this study considered how social pressures might relate to circadian rhythms, or the natural biological rhythms that dictate people’s sleep-wake cycles.

The researchers concluded that, on the whole, Americans’ sleep habits appear to be increasingly decoupled from natural patterns of sunlight — which might pose a number of negative health consequences for personal and collective wellbeing.

Twitter use and sleepnopporn/Shutterstock

The Rise Of “Twitter Social Jet Lag”

The researchers turned to Twitter to analyze social media usage, which helped the team identify patterns in Americans’ sleep schedules and relate them to seasonal and geographical factors.

Rust and his colleagues looked at geotagged Twitter data from more than 1,500 U.S. counties (or approximately half of all counties in the U.S.) spanning from 2011 to 2013. In total, these tweets represented approximately 240,000 people.

“Twitter data from this time period is a unique resource that records time and location of activity for [hundreds of thousands] of people in the U.S.,” Rust says.

By cross-checking this time-based and geographical Twitter data with other surveys regarding Americans’ sleep habits, the researchers were able to reasonably conclude that periods of inactivity on Twitter generally correspond to periods of sleeping, while Twitter activity generally corresponds to periods of wakefulness. This enabled them to track people’s sleep habits across different locales.

The data found that periods of Twitter inactivity occurred later on weekends than on weekdays, suggesting that social jet lag is widespread across the U.S. Many Americans’ weekday sleep patterns don’t seem to match their weekend sleep patterns, which suggests Americans may be working against their biological clocks for much of the week. Not surprisingly, these effects are magnified among shift workers.

Rates of social jet lag also seem to be strongly affected by seasonal and geographic factors. For example:

  • Most counties demonstrated a drop in Twitter social jet lag during the summer. The highest levels of Twitter social jet lag were between February and March and between September and October, while the lowest levels of social jet lag occurred in June and July. This suggests that social factors in the form of shifting school schedules might have more of an effect on people’s sleep habits than day length.
  • West coasters seem to display less social jet lag (at least according to their Twitter usage) than people in the east and central U.S. “It’s completely a guess right now, but I think it may be that people on the West Coast tend to spend more time outdoors, which may cause their biological clocks to be a little earlier, and help them sleep better,” Rust says.
  • Twitter social jet lag is lower among populations with more flexible scheduling. Counties with older populations, large numbers of college students, and later commute times all demonstrated lower Twitter social jet lag. The researchers suspect this is because these populations have more flexibility in setting their weekday schedules. In contrast, counties with earlier commute times tend to demonstrate higher Twitter social jet lag.

All told, the researchers concluded that this data suggests social factors influence patterns in Twitter usage — and, by extension, patterns in sleeping — more so than seasonal changes in day length. That said, it’s important to note that Twitter users may not be entirely representative of the U.S. population as a whole.

Man napping in hammockMonkey Business Images/Shutterstock

The Negative Consequences Of Social Jet Lag

Rust says adopting sleep patterns that are in conflict with a person’s biological clock can result in several negative impacts.

“Many studies suggest that there are negative health consequences, like obesity risk [and] risk of cardiovascular disease, when you try to “fight” your biological clock and work at times when your body wants to sleep,” Rust says. Social jet lag is also correlated with smoking, alcohol and caffeine consumption, mood disorders such as depression, and reduced academic performance.

Social jet lag may be exacerbated when people don’t obtain adequate exposure to natural sunlight.

“Not having a strong input from the sun can make your biological clock shift later into the day and might make these patterns more likely,” Rust says. “There’s a lot of work that indicates that the bright light you get from the sun when you’re outdoors is the major signal that our biological clocks use to set the time. On average, we’re spending less time outdoors and more time indoors doing things under dim artificial lighting at all hours of the day, compared to earlier generations.”

The good news is that one of the causes of social jet lag might also point toward a solution.

“A simple thing many people may be able to do in their lives is to try to ensure you get exposed to sunlight regularly in the morning, and it may help with many sleep and body clock problems,” Rust says.

[Editor’s Note: The content provided on this site is for general informational purposes only. Any information provided is not a substitute for professional medical advice. We encourage individuals to consult with the appropriate health expert if they have concerns.]

Featured image: Evgeny Atamanenko/Shutterstock

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Laura Newcomer

Laura Newcomer is the Editorial Controller at Mattress Clarity, where she occasionally writes sleep news. She's worked as a professional writer and editor for over a decade and has been published in or on outlets such as TIME, Washington Post, Inc., Entrepreneur, Huffington Post, Women's Health, and many more. Her primary areas of interest include sleep, fitness, nutrition, eco-friendly living, education, and all things wellness.