relationships between age, morning-type and rigidity sleeping habits with shiftwork tolerance

shiftwork is now a major feature of working life across a broad range of industries and circadian rhythms play an important role in shiftwork tolerance. so, the aim of this study was examine the relationships between age, morning-type and rigidity sleeping habits with shiftwork tolerance among shiftworkers of karun oil and gas exploitation company. the sample consisted of 295 shiftworkers of ahvaz, iran, selected according to the stratified random sampling. survey of shiftworkers (sos) was used to measure the variables of this study. the results indicate that correlation coefficients between the shiftwork tolerance with age, morning-type and rigidity sleeping habits were negative and significant ( p <.0001). stepwise multiple regression analyses yielded r1=0.449, r2=0.532 and r3=0.547 between shiftwork tolerance and independent variable. the results showed the importance of age, morning-type and rigidity as predictors of shiftwork tolerance. at a more practical level the main implication would be that we should attempt to select people for shiftwork systems according to their circadian rhythms (morningness /eveningness), sleeping habits (flexibility/rigidity) and demographic variables (such as age).