Lead researcher Talayeh Aledavood from Aalto University, Finland, said, "Each individual follows their own distinctive and persistent daily rhythm. These personal rhythms could be detected in multiple datasets, and to a similar extent for e-mail, phone calls, and text messages. In almost every case, the individual patterns differ strongly from the average behavior, for example by increased calling frequency during mornings, mid-days, or evenings."
What drives these individual differences is still unclear. Geographical and cultural differences play a role in it. The researchers suggest that there could also be an effect of physiology, for example caused by the difference between morning and evening persons, or by highly-individual patterns of alertness during the daylight hours.
This finding could also have certain medical applications. The researchers said, "Digital rhythms could be selectively monitored for patients with mental health problems. Sudden changes in patients' digital rhythms could be a sign that medical intervention may be necessary."
The findings were published in Frontiers in Physics.