[The neurobiology of sleep and its influence on memory].
OBJECTIVE
Recent developments in neuroscience have increased our knowledge of the physiology of sleep and dreaming, and thus the number of studies about the influence of sleep on learning and memory have increased rapidly. In this review the objective is to assess the relationship between sleep and memory considering the evidence regarding the neurobiology of sleep and dreaming.


METHODS
This is a retrospective literature review and the relevant studies from the last 10 years are included. For this purpose the PubMed search engine and the key words "sleep, neurobiology, synaptic plasticity, memory" were used.


RESULTS
Sleep-wake and NREM-REM cycles are accompanied by neuromodulatory influences on forebrain structures that affect behavior, consciousness and cognition. Animal and human studies in which learning paradigms are used to assess the influence of sleep deprivation on memory show the influence of sleep on memory consolidation. Different sleep stages have different effects on memory processes. Some investigators claim that NREM improves declarative memory while REM improves procedural and implicit memory. Other investigators suggest that NREM and REM affect memory in a complementary and sequential way. Molecular and electrophysiological evidence suggests that the influence of sleep on memory is through synaptic plasticity.


CONCLUSIONS
Studies about the physiology of sleep and dreaming will help us to understand consciousness and memory better. The reverse is also true: understanding the contribution of sleep stages to memory will help us to determine the advantages of sleep and dreaming in an evolutionary perspective.
Ertuğrul
Aygün
A
Rezaki
Murat
M
D006801:Humans; D008568:Memory; D009446:Neurobiology; D012189:Retrospective Studies; D012890:Sleep; D012892:Sleep Deprivation