They were shift workers who used to work in rotating 8-hour shift schedules, morning shifts (5:00 AM to 1:00 PM), mid-day shifts (1:00 PM to 9:00 PM) and overnight shifts (9:00 PM to 5:00 AM). All individuals signed an informed consent form before entering the study. The study was funded by the Vice Chancellor for Research and Technology of Shiraz University of Medical Sciences, Shiraz, Iran and it was approved by the university ethics committee. Fasting blood and urine samples were taken from all participants for urinalysis and biochemical tests of liver and kidney functions,which were performed by an automatic Italian made auto analyzer