Sex Difference in Morningness - Eveningness

Recently, interindividual differences in tolerance to shift work have become an increasing interest in chronobiological shift work studies.1) A number of factors have been investigated2) such as sex, age, general health status, quality and quantity of sleep, internal desynchronization between body temperature and sleep-wake cycle, morningness-eveningness, introversion-extroversion, job satisfication, etc. Among them, the morningness-eveningness (M-E) preference has received much attention since the publication of the M-E questionnaire in an English version of the report by Home and Ostberg.3) This questionnaire was translated into other languages and its validity has been confirmed by many authors.4-10) However, the sample populations were students in most of these studies,5-9) so that it remains to be determined whether there are differences between students and other populations (for example, shift workers). The present study was carried out to compare the M-E preference, with respect to sex difference, between students and shift-working hospital nurses using a Japanese version of the M-E questionnaire. An English version of the M-E questionnaire of Home and Ostbere3) was translated into Japanese, and this questionnaire was administered to 248 students