SHORT PAPER Morningness-eveningness preference, and mental and physical symptoms during the menstrual cycle of Japanese junior high school students.

Morningness-eveningness (M-E) preference and whether it was related to varying mental and physical conditions during the menstrual cycle of female students attending a Japanese junior high school, located in the suburban region in Nangoku city (33.3 N), Kochi prefecture, was studied. Those students who were beyond their first year after menarche were more evening-typed than those who were in their first year of menarche or those who had not yet begun their menstrual function. The M-E preference has no significant correlation with mood, periodical stability of the menstrual cycle or menstrual pain. The bedtime of those students who had an irregular menstrual cycle was significantly later than that of the students who had a stable cycle. [ABSTRACT FROM AUTHOR]