Digital daily cycles of individuals

Talayeh Aledavood, Sune Lehmann Jørgensen, Jari Saramäki

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Humans, like almost all animals, are phase-locked to the diurnal cycle. Most of us sleep at night and are active through the day. Because we have evolved to function with this cycle, the circadian rhythm is deeply ingrained and even detectable at the biochemical level. However, within the broader day-night pattern, there are individual differences: e.g., some of us are intrinsically morning-active, while others prefer evenings. In this article, we look at digital daily cycles: circadian patterns of activity viewed through the lens of auto-recorded data of communication and online activity. We begin at the aggregate level, discuss earlier results, and illustrate differences between population-level daily rhythms in different media. Then we move on to the individual level, and show that there is a strong individual-level variation beyond averages: individuals typically have their distinctive daily pattern that persists in time. We conclude by discussing the driving forces behind these signature daily patterns, from personal traits (morningness/eveningness) to variation in activity level and external constraints, and outline possibilities for future research.
Original languageEnglish
Article number73
JournalFrontiers of Physics
Number of pages7
Publication statusPublished - 2015

Bibliographical note

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).


  • Circadian rhythms
  • Electronic communication records
  • Mobile phones
  • Digital phenotyping
  • Individual differences


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