Sleep isn't lost time, Instead, it's a critical function, during which your body balances and
regulates its vital systems, affecting respiration and regulating everything from circulation to
growth and immune response.
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Well, not so fast. It turns out that sleep is also crucial for your brain, with a fifth of your body's
circulatory blood being channeled to it as you drift off. And what goes on in your brain while you
sleep is an intensely active period of restructuring that's crucial for how our memory works.
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At first glance, our ability to remember things doesn't seem very impressive at all. 19th century
psychologist Herman Ebbinghaus demonstrated that we normally forget 40% of new material
within the first twenty minutes, a phenomenon known as the forgetting curve.
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But this loss can be prevented through memory consolidation, the process by which information
is moved from our fleeting short-term memory to our more durable long-term memory.
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This consolidation occurs with the help of a major part of the brain, known as the hippocampus.
Its role in long-term memory formation was demonstrated in the 1950s by Brenda Milner in her
research with a patient known as Henry Molaison. What this case revealed, among other things,
was that the hippocampus was specifically involved in the consolidation of long-term declarative
memory, such as the facts and concepts you need to remember for that test, rather than
procedural memory, such as the finger movements that you need to master for that piano´s
recital.
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Milner's findings, along with work by Eric Kandel in the 90's, have given us our current model of
how this consolidation process works. Sensory data is initially transcribed and temporarily
recorded in the neurons as short-term memory. From there, it travels to the hippocampus, which
strengthens and enhances the neurons in that cortical area. Thanks to the phenomenon of
neuroplasticity, new synaptic buds are formed, allowing new connections between neurons, and
strengthening the neural network where the information will be returned as long-term memory.
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So why do we remember some things and not others? Well, there are a few ways to influence
the extent and effectiveness of memory retention. For example, memories that are formed in
times of heightened feeling, or even stress, will be better recorded due to the hippocampus' link
with emotion. But one of the major factors contributing to memory consolidation is, you guessed
it, a good night's sleep.
