Changes in sleep duration, timing, and variability during the COVID-19 pandemic: Large-scale Fitbit data from 6 major US cities

Published:March 23, 2021DOI:


      The COVID-19 pandemic has resulted in societal-level changes to sleep and other behavioral patterns. Objective data would allow for a greater understanding of sleep-related changes at the population level. About 163,524 active Fitbit users from 6 major US cities contributed data, representing areas particularly hard-hit by the pandemic (Chicago, Houston, Los Angeles, New York, San Francisco, and Miami). Sleep variables extracted include nightly and weekly mean sleep duration and bedtime, and variability (standard deviation) of sleep duration and bedtime. Deviation from similar timeframes in 2018 and 2019 were examined, as were changes in these sleep metrics during the pandemic, relationships to changes in resting heart rate, and changes during re-opening in May and June. Overall, compared to 2019, mean sleep duration in 2020 was higher among nearly all groups, mean sleep phase shifted later for nearly all groups, and mean sleep duration and bedtime variability decreased for nearly all groups (owing to decreased weekday-weekend differences). Over the course of January to April 2020, mean sleep duration increased, mean bedtime shifted later, and mean sleep duration variability decreased. Changes in observed resting heart rate correlated positively with changes in sleep and negatively with activity levels. In later months (May and June), many of these changes started to drift back to historical norms.


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        • Grandner MA.
        Sleep, health, and society.
        Sleep Med Clin. 2017; 12: 1-22
        • Grandner MA
        • Patel NP
        • Hale L
        • Moore M.
        Mortality associated with sleep duration: the evidence, the possible mechanisms, and the future.
        Sleep Med Rev. 2010; 14: 191-203
        • Grandner MA.
        Social-ecological model of sleep health.
        in: Grandner MA Sleep and Health. Academic Press, London2019: 45-53
        • Crew EC
        • Baron KG
        • Grandner MA
        • et al.
        The Society of Behavioral Sleep Medicine (SBSM) COVID-19 Task Force: objectives and summary recommendations for managing sleep during a pandemic.
        Behav Sleep Med. 2020; 18: 570-572
        • Fitbit Inc.
        Fitbit Terms of Service.
        Fitbit, San Francisco, CA2018
        • Beattie Z
        • Pantelopoulos A
        • Ghoreyshi A
        • Oyang Y
        • Statan A
        • Heneghan C.
        Estimation of sleep stages using cardiac and accelerometer data from a wrist-worn device.
        SLEEP. 2017; 40: A26
        • Lauderdale DS
        • Knutson KL
        • Rathouz PJ
        • Yan LL
        • Hulley SB
        • Liu K.
        Cross-sectional and longitudinal associations between objectively measured sleep duration and body mass index: the CARDIA Sleep Study.
        Am J Epidemiol. 2009; 170: 805-813
        • Ancoli-Israel S
        • Martin JL
        • Blackwell T
        • et al.
        The SBSM guide to actigraphy monitoring: clinical and research applications.
        Behav Sleep Med. 2015; 13: S4-S38
        • de Zambotti M
        • Baker FC
        • Willoughby AR
        • et al.
        Measures of sleep and cardiac functioning during sleep using a multi-sensory commercially-available wristband in adolescents.
        Physiol Behav. 2016; 158: 143-149
      1. Chinoy ED, Cuellar JA, Huwa KE, et al. Performance of seven consumer sleep-tracking devices compared with polysomnography. Sleep. In press.

        • Bonnet MH
        • Arand DL.
        EEG arousal norms by age.
        J Clin Sleep Med. 2007; 3: 271-274
        • Nazari G
        • MacDermid JC
        • Sinden KE
        • Richardson J
        • Tang A.
        Inter-instrument reliability and agreement of fitbit charge measurements of heart rate and activity at rest, during the modified Canadian aerobic fitness test, and in recovery.
        Physiother Can. 2019; 71: 197-206
        • Lee E
        • Ramsey M
        • Malhotra A
        • et al.
        Links between objective sleep and sleep variability measures and inflammatory markers in adults with bipolar disorder.
        J Psychiatr Res. 2020; 134: 8-14
      2. Ong JL, Lau TY, Massar SAA, et al. COVID-19 related mobility reduction: heterogeneous effects on sleep and physical activity rhythms. Archiv. 2020:2006.02100 [q-bio.QM]. In press.

        • Quer G
        • Gouda P
        • Galarnyk M
        • Topol EJ
        • Steinhubl SR.
        Inter- and intraindividual variability in daily resting heart rate and its associations with age, sex, sleep, BMI, and time of year: Retrospective, longitudinal cohort study of 92,457 adults.
        PLoS One. 2020; 15e0227709
        • Caetano J
        • Delgado Alves J
        Heart rate and cardiovascular protection.
        Eur J Intern Med. 2015; 26: 217-222
        • Minges KE
        • Redeker NS.
        Delayed school start times and adolescent sleep: a systematic review of the experimental evidence.
        Sleep Med Rev. 2016; 28: 86-95
        • Wheaton AG
        • Chapman DP
        • Croft JB.
        School start times, sleep, behavioral, health, and academic outcomes: a review of the literature.
        J Sch Health. 2016; 86: 363-381
        • Troxel W
        • Wolfson A.
        Sleep science and policy: a focus on school start times.
        Sleep Health. 2016; 2: 186
        • Wright Jr., KP
        • Linton SK
        • Withrow D
        • et al.
        Sleep in university students prior to and during COVID-19 stay-at-home orders.
        Curr Biol. 2020; 30: R797-R7R8
        • Ong JL
        • Lau T
        • Massar SAA
        • et al.
        COVID-19 related mobility reduction: heterogenous effects on sleep and physical activity rhythms.
        Sleep. 2020; (In press)
        • Lee PH
        • Marek J
        • Nalevka P.
        Sleep pattern in the US and 16 European countries during the COVID-19 outbreak using crowdsourced smartphone data.
        Eur J Public Health. 2020; (In press)
        • Blume C
        • Schmidt MH
        • Cajochen C.
        Effects of the COVID-19 lockdown on human sleep and rest-activity rhythms.
        Curr Biol. 2020; 30: R795-R7R7
        • Pesonen AK
        • Lipsanen J
        • Halonen R
        • et al.
        Pandemic dreams: network analysis of dream content during the COVID-19 lockdown.
        Front Psychol. 2020; 11573961
        • Kocevska D
        • Blanken TF
        • Van Someren EJW
        • Rosler L.
        Sleep quality during the COVID-19 pandemic: not one size fits all.
        Sleep Med. 2020; 76: 86-88
        • Bigalke JA
        • Greenlund IM
        • Carter JR.
        Sex differences in self-report anxiety and sleep quality during COVID-19 stay-at-home orders.
        Biol Sex Differ. 2020; 11: 56
        • Killgore WDS
        • Cloonan SA
        • Taylor EC
        • Fernandez F
        • Grandner MA
        • Dailey NS.
        Suicidal ideation during the COVID-19 pandemic: the role of insomnia.
        Psychiatry Res. 2020; 290113134
        • Werneck AO
        • Silva DR
        • Malta DC
        • et al.
        The mediation role of sleep quality in the association between the incidence of unhealthy movement behaviors during the COVID-19 quarantine and mental health.
        Sleep Med. 2020; 76: 10-15
        • Maas MB
        • Kim M
        • Malkani RG
        • Abbott SM
        • Zee PC.
        Obstructive sleep apnea and risk of COVID-19 infection, hospitalization and respiratory failure.
        Sleep Breath. 2020; (In press)