The effect of time of day of instruction on achievement

A theory involving short-term memory (STM) and longterm memory (LTM) suggests that tasks that involve mainly the use of STM are learned and performed better in the morning; tasks that involve mainly the use of LTM are learned and performed better in the afternoon. Two physiological factors account for time-of-day differences in learning: (a) basal arousal rises from a low level in the morning to a peak in the evening, and the use of STM and LTM are associated with it, respectively;{b} diurnal rhythms in plasma and hormone levels influence the way people encode, store, and retrieve information and are associated with better LTM processing later in the day and better STM processing earlier in the day.