ABSTRACT
Psychologists have long been interested in variations in behavior over the course of the day. The first article in the first issue of The American Journal of Psychology (the first psychology journal published in the US) reported data on the impact of time of day on the magnitude of the knee jerk response (Lombard, 1887). Much of this work has assumed that there is one general pattern or one optimal time of day that characterizes everyone’s performance, regardless of variables such as age (e.g., Baddeley, Hatter, Scott, & Snashall, 1970; Blake, 1967; but see Bergstrum, 1894, for an early, albeit rare, exception). This neglect of individual and developmental differences is mirrored in longstanding western cultural beliefs, as indexed by aphorisms such as “early to bed, early to rise, makes a man healthy, wealthy, and wise” or “the early bird gets the worm.” The message is clear: it is best for all of us to be morning people.
