Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: May 16, 2019
Date Accepted: Nov 18, 2019
Date Submitted to PubMed: Feb 20, 2020
Four-Year Trends in sleep duration and quality in New York City based on 2 million nights of data from users of a smartphone sleep tracker
ABSTRACT
Background:
Population estimates of sleep duration and quality are inconsistent because they rely primarily on self-reported data. Passive and ubiquitous digital tracking and wearable devices may provide more accurate estimates of sleep duration and quality.
Objective:
Our objective was to identify trends in sleep duration and quality in New York City based on 2 million nights of data from users of a popular mobile sleep application (app).
Methods:
We examined sleep duration and quality using 2,161,067 nights of data captured from 2015 to 2018 by SleepCycle, a popular sleep-tracking app. In this analysis, we explored differences in sleep parameters based on demographic factors, including age and sex. We utilized graphical matrix representations of data (heat maps) and geospatial analyses to compare sleep duration (in hours) and sleep quality (based on time in bed, deep-sleep time, sleep consistency, and number of times fully awake), considering potential effects of day of the week and seasonality.
Results:
Women represented 1,003,421 out of 2,161,067 (45.6%) of the sample and males represented 1,157,646 out of 2,161,067 (53.6%) individuals in the sample. The average age of the sample was 31.0 years (s.d.=10.6 years). The mean sleep duration of the total sample was 7.11 hours (s.d.=1.4). Women slept longer on average (mean = 7.27 hours, s.d.=1.4) than did men (mean = 7.00 hours, s.d.=1.3, p < 0.001). Trend analysis indicated longer sleep duration and higher sleep quality among older individuals as compared to younger (p<.001). On average, sleep duration was longer on the weekend (mean = 7.19 hours, s.d.=1.5), compared to weeknights (mean = 7.09 hours, s.d.=1.3, , p-value<.001).
Conclusions:
Our study of data from a commercially available sleep tracker showed that women experienced longer sleep duration and higher sleep quality in nearly every age group as compared to men, and a low proportion of young adults obtained the recommended sleep duration. Future research may compare sleep measures obtained via wearable sleep trackers with validated research-grade measures of sleep.
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