Sleep and memory

Memory is the cognitive process whereby experiences, learning and recognition are recalled. Memory “formation” is a product of brain plasticity, the structural changes within synapses that create associations between stimuli. Stimuli are encoded within milliseconds, however the long-term maintenance of memories can take additional minutes, days, or even years to fully consolidate and become a stable memory (more resistant to change or interference). Therefore, the formation of a specific memory occurs rapidly, but the evolution of a memory is often an ongoing process.

Memory processes have been shown to be stabilized and enhanced (sped up and/or integrated) by nocturnal sleep and even daytime naps. Certain sleep stages are noted to improve an individual’s memory, although this is task specific. Generally, declarative memories are enhanced by slow-wave sleep, while non-declarative memories are enhanced by rapid eye movement (REM) sleep, although there are some inconsistencies among experimental results.