Grandner M, et al. Abstract 214. Presented at: SLEEP; June 10-13, 2021 (virtual meeting).

Disclosures: Fitbit, Inc. supported the study. No other relevant financial disclosures were reported.
June 14, 2021
2 min read

Sleep duration increases, particularly among young adults, during COVID-19 pandemic


Grandner M, et al. Abstract 214. Presented at: SLEEP; June 10-13, 2021 (virtual meeting).

Disclosures: Fitbit, Inc. supported the study. No other relevant financial disclosures were reported.
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Mean sleep duration increased in 2020 by 5 to 11 minutes in nearly all groups studied, according to an analysis of Fitbit data from more than 163,000 users in six major U.S. cities “particularly hard hit” by the COVID-19 pandemic.

The researchers compared the results from 2020 with results from 2019, which demonstrated a mean decrease in sleep duration of 5 to 8 minutes. They reported P values of less than .00001 regarding the increase in sleep duration observed in 2020.

Mean sleep duration increased in nearly all groups by 5 to 11 minutes in 2020, compared with a mean decrease of 5 to 8 minutes in 2019.
Reference: Grandner M, et al. Abstract 214. Presented at: SLEEP; June 10-13, 2021 (virtual meeting).

Researchers first published the findings in Sleep, the journal of the Sleep Research Society, and presented recently at the society’s annual meeting, which was held virtually.

“The most surprising thing we found was that, overall, sleep duration increased slightly, and sleep variability decreased slightly, during the most intense months of the pandemic,” Michael Grandner, PhD, MTR, CBSM, FAASM, director of the sleep and health research program and associate professor of clinical translational sciences, medicine, psychiatry and psychology at the University of Arizona College of Medicine — Tucson, said in a press release. “It was also interesting to see that the degree of change in sleep was correlated with the degree of improvement in resting heart rate.”

Grandner and colleagues noted that the COVID-19 pandemic caused “societal-level changes to sleep and other behavioral patterns.” They wrote that objective, longitudinal data would provide researchers with a “greater understanding” of sleep-related changes during this period at the population level.

The researchers examined deidentified data from 163,524 active Fitbit users in Chicago, Houston, Los Angeles, New York, San Francisco and Miami. Grandner and colleagues collected data on sleep variables, including nightly and weekly mean sleep duration and bedtime, variability of sleep duration and bedtime, and approximated arousals and sleep stages. They also extracted data on deviation from similar time periods in 2019.

The year 2020 represented “a significant departure” in sleep among all age groups, as well as both men and women, according to the study results (P < .00001). Mean sleep duration increased among nearly all groups by 5 to 11 minutes (P < .00001). The researchers compared these data with the same period in 2019, in which mean sleep duration decreased by 5 to 8 minutes.

“Categorically, sleep duration increased for some and decreased for others, but more extended than restricted,” the researchers wrote.

Grandner and colleagues also found that sleep phase shifted later for nearly all groups examined (P < .00001).

“Categorically, bedtime was delayed for some and advanced for others, though more delayed than advanced,” the researchers wrote. “Duration and bedtime variability decreased, owing largely to decreased weekday–weekend differences.”

Wake after sleep onset and the percentage of rapid eye movement sleep both increased, while the percentage of deep sleep decreased, according to the study results. Further analyses demonstrated stratified, longitudinal differences in sleep duration, as well as timing mean and variability distributions by month.

“The increase [in sleep duration] was most profound among younger adults, especially women. The youngest adults also experienced the greatest bedtime delay, in line with extensive school start times and chronotype data,” the researchers wrote. “When given the opportunity, the difference between weekdays and weekends became smaller, with occupational implications.”

According to Grandner, the results may represent “the largest study of objective sleep recordings from a geographically diverse general population sample” taken at the height of the pandemic.

“They are also important because they document important population trends, such as delayed bedtime and extended sleep, perhaps due to stay-at-home orders,” he said in the press release.


SLEEP 2021. Fitbit user data show slight increase in sleep duration in U.S. during COVID-19 pandemic. Available at: Accessed June 14, 2021.