Evaluation of the Effect of Time Change in Cognitive Function in Volunteers in Tehran.

BACKGROUND Time change (which can lead to sleep duration decrements) can lead to brain dysfunction if repeated. In the present study, cognitive functions of the volunteers were evaluated before and after the time changes in Tehran. METHODS Eleven, voluntary healthy persons (21±2 year old) were evaluated for their cognitive functions including sustain attention, reaction time, and mental fatigue twenty-one days before the time changes and thirty-eight days after time change using PASAT software. In addition, plasma cortisol level was measured before and after the time changes. RESULTS After the time changes salivary cortisol concentration increase, but general mental health was decreased. Sustain attention was shortened after time change which was significantly different compared with before the time changes. Reaction time was increased after the time changes in comparison with the before the time changes, but was not statistically significant. In addition, mental fatigue was increased after the time changes. CONCLUSION It seems that time change may reduce brain cognitive functions which are manifested by general mental health, sustain attention reduction, reaction time as well as mental fatigue.