Day persons, night persons, and time of birth: preliminary findings

The authors conducted 2 surveys to determine the relationship between time of birth and being a day person or a night person. Day persons are most alert during daylight hours; night persons are most alert during hours of darkness. In Survey 1, the authors asked U.S. high school students to complete the Alertness Questionnaire (B. Wallace, 1993) and to respond to other items related to daytime or nighttime activity. In Survey 2, the authors administered the same items to a U.S. college population. In both surveys, time of birth was significantly related to being a day person or a night person. The results suggest that a critical period for setting the biological clock for alertness may be the moment of birth.