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You, too, have a bodily rhythm – and it affects your behaviour

Leiden researchers Arko Ghosh and Enea Ceolini analysed the usage data of hundreds of mobile phones and discovered that our body has rhythms ranging between 7 and 52 days. These cycles influence how we behave. Their research resulted in an article in npj Digital Medicine journal, a Nature Portfolio publication.

‘If people think they just live their lives, deciding their behaviour for themselves, and that there is no overarching structure, they’ve got it wrong,’ says researcher Arko Ghosh. Together with his colleague Enea Ceolini, he carried out research on recurring patterns – rhythms – in human behaviour. Their research led to the unexpected outcome that absolutely everyone has these rhythms.

The idea of a rhythm that your body reacts to is not new. Women have the menstrual cycle, for example, and some people also believe that the lunar cycle influences how we behave. There is a lot of scientific debate about the lunar cycle, but it is a known fact that psychological and neurological conditions like bipolar condition and epilepsy follow a cycle of several days. A pattern can be seen, for example, in epileptic attacks that occur every so many days.

Discrimination of women

Ghosh and Ceolini have shown that recurring patterns do not occur only in these kinds of psychological and  neurological conditions, but that everyone has cycles lasting several days. Ghosh: These cycles influence our behaviour. How they influence that behaviour and what behaviour relates to what particular times in the cycle is something we haven’t studied yet. But in our analyses of the data on the mobile phones of our test subjects, we made a striking discovery. We found that cycles of several days are very common: in old and young people, and in women and men. That last point is particularly remarkable.  

A lot of women face discrimination at work because their performance is often thought to suffer as a result of their menstrual cycle. Our research shows that women are not the only ones with a cycle. Men have a cycle, too, of 25 to 30 days, which also affects their behaviour.’   

The results may also have an impact on the research on psychological and neurological conditions.  Ghosh: ‘Are the cycles we see here caused by the illness, or are they “normal” cycles that become more apparent as a result of the illness?’

Tracking on mobile phones

Some 400 subjects, aged 16 to 80, responded to a call to participate in the study. The prerequisite to participate? An Android phone. An app was installed on it that allowed the researchers to track and analyse usage data. Ghosh: 'We only looked at the times when people were actively using their phones and were swiping or typing. We couldn’t see what they were doing with their phones, and we didn’t need to see that. We didn’t ask such things as what their mood was like at that point in time. That’s not what we were interested in.’   

Smartphone use can be divided into different kinds of behaviour. By looking at this behaviour on the basis of how people touched the screen and the time between touches, we distinguished 2,500 different types of smartphone use.

Some mannerisms had a pattern that repeated every 25 days, such as when there was a long pause between touches. Others had a pattern that repeated every 19 days, such as when there was a short pause between touches. In short, we found that people use their smartphones in many different ways and that some of these ways have a pattern that is repeated after a certain period of time.

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Predicting behaviour

It is not yet clear how the recurring patterns arise, but the complex interchange between our environment and our own cognitive skills may play a role. Ghosh stresses that two people may have the same cycle, but that they may respond completely differently to it. Further research can bring us more insights. Ghosh: ‘We might then be able to predict particular behaviour on the basis of a person’s cycle. This might in turn lead to a completely new definition of what is normal behaviour and what is behaviour that is related to a neurological or psychological condition.’

Arko Ghosh and Enea Ceolini are part of the CODELAB team (Cognition in the digital environment laboratory), where research is carried out on how neurological and psychological processes influence our daily life.  The article on Common multi-day rhythms in smartphone behavior door Arko Ghosh en Enea Ceolini can be read in the reputable npj Digital Medicine, a Nature Portfolio publication.

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