We have learned how sleep helps the brain to retain and store memories. For example, our brains fast-forward the memories of the day in the hippocampus, which is the brain's central memory-filing system. This strengthens the nerve cell connections and in sleep, specific activities are replayed, sorted, and selectively retained. During sleep, this memory information is transferred from the hippocampus to the cerebral cortex for long term memory.
Sleep enhances the 'consolidation of memories.' First, it shuts off the interference of everyday sensory stimuli so that the brain can concentrate on the memories. Not only that, according to a new study by the Scripps Research Institute, sleeping keeps the memory consolidation process steady by blocking some of the neurotransmitter dopamine, thereby reducing the forgetting signals in the brain. Memories are consolidated by a process called ‘sleep spindles’ where half-second to two-second bursts of brain activity are processed in the brain.
Another interesting new finding is that when we learn something new, it does not erase the older memory, but instead, it stores this additional memory alongside the original memories of the same experience. According to Dr. Scott Cairney, lead researcher at the University of York, “sleep is allowing us to use our memory in the most efficient way possible, enabling us to update our knowledge of the world and to adapt our memories for future experiences.”
So, remember that when you sleep, you’re doing great things for your memories. Sleep is good!