REM sleep and memory processing

The role of rapid eye movement sleep for amygdala-related memory processing.
Genzel L, Spoormaker V, Konrad BN, Dresler M.
Neurobiol Learn Mem. 2015 Jan 28.

Over the years, rapid eye movement (REM) sleep has been associated with general memory consolidation, specific consolidation of perceptual, procedural, emotional and fear memories, brain maturation and preparation of waking consciousness. More recently, some of these associations (e.g. general and procedural memory consolidation) have been shown to be unlikely, while others (e.g. brain maturation and consciousness) remain inconclusive. In this review, we argue that both behavioral and neurophysiological evidence supports a role of REM sleep for amygdala-related memory processing: the amygdala-hippocampus-medial prefrontal cortex network involved in emotional processing, fear memory and valence consolidation shows strongest activity during REM sleep, in contrast to the hippocampus-medial prefrontal cortex only network which is more active during non-REM sleep. However, more research is needed to fully understand the mechanisms.

Sleep, cognition and aging

Sleep, Cognition, and Normal Aging: Integrating a Half-Century of Multidisciplinary Research.
Scullin MK, Bliwise DL.
Perspect Psychol Sci. 2015 Jan;10(1):97-137. 

Sleep is implicated in cognitive functioning in young adults. With increasing age there are substantial changes to sleep quantity and quality including changes to slow wave sleep, spindle density, and sleep continuity/fragmentation. A provocative question for the field of cognitive aging is whether such changes in sleep physiology affect cognition (e.g., memory consolidation). We review nearly a half-century of research studies across 7 diverse correlational and experimental literature domains, which historically have had little crosstalk. Broadly speaking, sleep and cognitive functions are often related in advancing age, though the prevalence of null effects (including correlations in the unexpected, negative direction) in healthy older adults indicates that age may be an effect modifier of these associations. We interpret the literature as suggesting that maintaining good sleep quality, at least in young adulthood and middle age, promotes better cognitive functioning and serves to protect against age-related cognitive declines.

Sleep duration recommendations

National Sleep Foundation recently published an update to the sleep duration recommendations.