  Explosion of number of smartphone apps and their diversity has created a
fertile ground to study behaviour of smartphone users. Patterns of app usage,
specifically types of apps and their duration are influenced by the state of
the user and this information can be correlated with the self-reported state of
the users. The work in this paper is along the line of understanding patterns
of app usage and investigating relationship of these patterns with the
perceived stress level within the workplace context. Our results show that
using a subject-centric behaviour model we can predict stress levels based on
smartphone app usage. The results we have achieved, of average accuracy of 75%
and precision of 85.7%, can be used as an indicator of overall stress levels in
work environments and in turn inform stress reduction organisational policies,
especially when considering interrelation between stress and productivity of
workers.
