Table 1: Sociodemographic characteristics of the sample ().

Variables % Sex      Male 297 41  Female 431 59 Mean age ± SD      Male 32.74 (±5.99)    Female 31.35 (±5.03)   Marital status      Single 222 30  Married 506 70 Education      Junior college or vocational school  equivalency degree 401 55  College graduate or higher 327 45 Type of job      Clerical post 81 11  Computer technical support 636 87  Managerial post 11 2 Shift work      Without 252 35  With 476 65 Mean working hours per day      Less than seven or fewer hours per day 59 8  Eight hours per day 384 53  Nine hours per day 161 22  Ten hours per day 94 13  More than eleven hours per day 30 4 Frequency of working on days off      Non 581 80  More than one day on a monthly basis 147 20