Wednesday, August 12, 2009

Circadian rhythm in handwriting

The aim of the present study was to determine whether the motor process of handwriting is influenced by a circadian rhythm. Nine healthy young male subjects underwent a 40-h sleep deprivation protocol under constant routine conditions. Starting at 09:00 hours, subjects performed every 3 h two handwriting tasks of different complexity. Handwriting performance was evaluated by writing speed, writing fluency and script size. The frequency of handwriting, as a measure of movement speed, revealed a circadian rhythm, validated by harmonic regression, with a slowing at the time of the onset of melatonin secretion (22:17 hours) and a trough in the very early morning at around 03:30 hours. In the temporal variability of handwriting an effect of task complexity was suggested in the direction of circadian variations in parallel with speed only for the sentence. Despite deficits of speed and temporal variability, writing fluency did not change significantly across sessions indicating that the basic automation of handwriting was preserved at any time. On the second day, daytime levels of the kinematics of handwriting did not reflect impaired performance after sleep deprivation. Our results show for the first time a clear circadian rhythm for the production of handwriting.

Article History:

Accepted in revised form 30 October 2008; received 7 July 2008

Article note:

Isabelle Jasper, Clinical Neuropsychology Research Group (EKN), Clinic for Neuropsychology, Munchen-Bogenhausen Hospital, Dachauerstrasse 164, D-80992 Munich, Germany. Tel.: +49 89 154058; fax: +49 89 156781; e-mail:

Source Citation:Jasper, Isabelle, Andreas Haussler, Christian Marquardt, and Joachim Hermsdorfer. "Circadian rhythm in handwriting." Journal of Sleep Research 18.2 (June 2009): 264(8). Academic OneFile. Gale. BROWARD COUNTY LIBRARY. 12 Aug. 2009
Gale Document Number:A200141990

Disclaimer:This information is not a tool for self-diagnosis or a substitute for professional care.

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