ABSTRACT
This chapter is concerned with the effects of circadian (about-24-h) rhythms on human memory processes. Following a brief historical overview, the arousal 242theory that has dominated research in this area is considered. The experimental literature is then reviewed on both the trend(s) in memory over the day, and the changes in encoding, storage, and/or retrieval responsible for these trends. The adequacy of the arousal theory in accounting for this literature is questioned, and some counterevidence from studies of the adjustment of circadian rhythms to a shift in the sleep-wake cycle is discussed. The chapter ends with a consideration of the practical and theoretical implications of time-of-day effects in human memory, and of the outstanding questions in this area that remain unanswered.
