Quantifying daily rhythms with non-negative matrix factorization applied to mobile phone data

Abstract

Human activities follow daily, weekly, and seasonal rhythms. The emergence of these rhythms is related to physiology and natural cycles as well as social constructs. The human body and its biological functions undergo near 24-h rhythms (circadian rhythms). While their frequencies are similar across people, their phases differ. In the chronobiology literature, people are categorized into morning-type, evening-type, and intermediate-type groups called chronotypes based on their tendency to sleep at different times of day. Typically, this typology builds on carefully designed questionnaires or manually crafted features of time series data on people’s activity. Here, we introduce a method where time-stamped data from smartphones are decomposed into components using non-negative matrix factorization. The method does not require any predetermined assumptions about the typical times of sleep or activity: the results are fully context-dependent and determined by the most prominent features of the activity data. We demonstrate our method by applying it to a dataset of mobile phone screen usage logs of 400 university students, collected over a year. We find four emergent temporal components: morning activity, night activity, evening activity and activity at noon. Individual behavior can be reduced to weights on these four components. We do not observe any clear categories of people based on the weights, but individuals are rather placed on a continuous spectrum according to the timings of their phone activities. High weights for the morning and night components strongly correlate with sleep and wake-up times. Our work points towards a data-driven way of characterizing people based on their full daily and weekly rhythms of activity and behavior, instead of only focusing on the timing of their sleeping periods.

Synchronization of online social rhythms via avatar communications

“…These rhythms are not only coordinated by white light stimuli but also affected by social cues [11]; for example, people coordinate their waking hours to attend work and school and to meet with friends. We can regard humans' circadian rhythms as coupled oscillators in a complex social network [12,13].This should also be valid for online social rhythms, that is, the rhythms of online social activities, which also tend to provide information on peoples' physical rhythms in their everyday lives [14,15]. People's communication activities are often driven by receiving online messages [16,17].…”

“…This should also be valid for online social rhythms, that is, the rhythms of online social activities, which also tend to provide information on peoples' physical rhythms in their everyday lives [14,15]. People's communication activities are often driven by receiving online messages [16,17].…”

A Large-Scale Characterization of How Readers Browse Wikipedia

“…For instance, in information science, time has long been recognized as a crucial contextual factor that drives human information seeking (Savolainen 2006). The study of traces recorded on digital platforms has yielded novel insights about circadian rhythms (Aledavood et al 2022;Pintér and Felde 2022;Althoff et al 2017;Murnane et al 2015;Chalmers et al 2011; Kumar Swain and Kumar Pati 2020; Leypunskiy et al 2018) and periodic fluctuations in alertness (Abdullah et al 2016), mood (Dodds et al 2011;Golder and Macy 2011), focus (Mark et al 2016), musical taste (Park et al 2019;Heggli, Stupacher, and Vuust 2021), purchase habits (Gullo et al 2019), and ad engagement (Saha et al 2021).…”

The impact of the COVID-19 pandemic on daily rhythms

“…Before the COVID-19 pandemic, different studies have investigated daily rhythms of activity, for example, in social interactions via calls [27], text messages [28], and emails [29], phone usage [30], sleep [31], or web browsing [32]. These studies have shown that, despite differences between individuals, people tend to keep consistent daily rhythms and allocate a similar portion of a certain activity (e.g., making phone calls) to each section of the day (e.g., morning, evening).…”