The effects of shift work and time of day on fine motor control during handwriting

Abstract

Handwriting is an elaborate and highly automatised skill relying on fine motor control. In laboratory conditions handwriting kinematics are modulated by the time of day. This study investigated handwriting kinematics in a rotational shift system and assessed whether similar time of day fluctuations at the work place can be observed. Handwriting performance was measured in two tasks of different levels of complexity in 34 shift workers across morning (6:00–14:00), evening (14:00–22:00) and night shifts (22:00–6:00). Participants were tested during all three shifts in 2- h intervals with mobile testing devices. We calculated average velocity, script size and writing frequency to quantify handwriting kinematics and fluency. Average velocity and script size were significantly affected by the shift work schedule with the worst performance during morning shifts and the best performance during evening shifts. Our data are of high economic relevance as fine motor skills are indispensable for accurate and effective production at the work place.

Abstract

Practitioner Summary: Handwriting is one of the most complex fine motor skills in humans, which is frequently performed in daily life. In this study, we tested handwriting repeatedly at the work place in a rotational shift system. We found slower handwriting velocity and reduced script size during morning shifts.

Keywords::

• field study
• fine motor control
• handwriting
• kinematic analysis
• rotating shift

Acknowledgements

This research was supported by the Siemens AG, and the Ladenburg Collegium ‘ClockWork’ funded by the Gottlieb Daimler- and Karl Benz-Foundation. We would like to thank all participants in the Siemens factories, Berlin, and their supervisors for organisational help. Many scientists and student helpers contributed to this study: Christian Tatarau who programmed the PDAs, Dr Christian Marquardt who supported the writing analysis, Dr Leiff Johannsen for corrections, Dr Isabelle Zierdt, Dr Daniel Bratzke, Dr Michael Steinborn, Andreas Häusler, Alexandra Obermayr, Gabriela Wypior, Lena Schwarzer and Franziska Scheller.