JMIR Publications

ABSTRACT

Background:

Circadian rhythm is known to be an important metronome of human activity reflecting both physical and psychical health states of the individual. Given the 'hyperconnected digital' world we live in and considering that phone has become a very important part of our lives, and our children’s lives, recent studies have judiciously and convincingly demonstrated the possibility of estimating such a rhythm on a digital way through the analysis of phone call detail records (CDRs). Interestingly, at individual-level, these studies have in common that, in general, the target groups of participants consisted mostly of young individuals, typically students or young actives. At this point, however, whether and how similar results could also be observed among older adults remains to be established.

Objective:

The present study is specifically designed to address the existence of circadian rhythms in phone calls in older adults at individual-level.

Methods:

We use a longitudinal 12-month dataset that combines CDRs and questionnaire data of 21 volunteers older than 65 years to examine individual differences in the daily rhythms of phone call activity. In this study, we use outgoing CDRs only from which we operate three specific telecommunication parameters: (1) phone call recipient (alter), (2) time and (3) duration of phone call. In line with the arguments proposed in recent studies on young adults, we specifically focus on three issues: (1) the existence of circadian rhythms by computing the average daily outgoing phone call activity of individuals, (2) the consistence of such patterns by evaluating their persistence through time, and (3) their alter-specificity by analyzing how individuals allocate their time of communication with their social network through the day by calculating relative entropy.

Results:

At individual-level, we show that older adults have their own specific circadian pattern in outgoing phone calls whose salient features vary across individuals from morning until nocturnal preferences for phoning. We further demonstrate that these circadian patterns are consistent which is reflected by their ability for persisting in time. Finally, results suggest that such patterns in outgoing phone call activity in older adults are partly structured by how individuals allocate their time of communication among their social network.

Conclusions:

On the whole, our results demonstrate, for the first time, the existence, persistence, and alter-specificity of circadian rhythms in outgoing phone call activity at individual-level in older adults. The significance and limitations of this study are discussed and a future research direction is proposed.