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. 2021 Mar 23;7(3):303–313. doi: 10.1016/j.sleh.2021.02.008

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© 2021 Published by Elsevier Inc. on behalf of National Sleep Foundation.

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Fig 8 — Histogram of change in variability (standard deviation) of sleep duration between January and April in 2020 and 2019. Change reflected decreases in variability in 2020 than 2019.