# Tracking Urban Human Activity from Mobile Phone Calling Patterns

## TL;DR

This study analyzes mobile phone calling patterns in large cities to understand urban human activity rhythms, revealing synchronization with sunlight and seasonal variations influenced by biological and social factors.

## Contribution

It demonstrates how urban calling activity patterns are entrained to natural light cycles and seasonal changes, using large-scale mobile data analysis.

## Key findings

- Calling activity onset aligns with the east-west sun progression
- Activity timings vary seasonally and are entrained to solar midnight
- Mid-sleep times depend on age and gender, influenced by biological and social factors

## Abstract

Timings of human activities are marked by circadian clocks which in turn are entrained to different environmental signals. In an urban environment the presence of artificial lighting and various social cues tend to disrupt the natural entrainment with the sunlight. However, it is not completely understood to what extent this is the case. Here we exploit the large-scale data analysis techniques to study the mobile phone calling activity of people in large cities to infer the dynamics of urban daily rhythms. From the calling patterns of about 1,000,000 users spread over different cities but lying inside the same time-zone, we show that the onset and termination of the calling activity synchronizes with the east-west progression of the sun. We also find that the onset and termination of the calling activity of users follows a yearly dynamics, varying across seasons, and that its timings are entrained to solar midnight. Furthermore, we show that the average mid-sleep time of people living in urban areas depends on the age and gender of each cohort as a result of biological and social factors.