# 35: Sleep and Memory - Part 1

The Matt Walker Podcast

It is a fundamental truth that sleep is far more than the absence of wakefulness. It is an incredibly active state, demonstrated by the fact that numerous functions of the brain and body are restored by and depend on sufficient sleep. One of the most impressive and best-understood of these is sleep’s beneficial role in boosting learning and memory abilities. Sleep is necessary both before and after learning and it intelligently associates and interconnects new memories together, offering the ability for creativity and ingenuity.

The first of these benefits starts while we’re awake, as the brain acquires novel information, and different types of memories are imprinted in different parts of it. Fact-based memories depend on an area of the brain called the hippocampus, which is almost like a USB stick. Some years ago, Matt and his team conducted a study on the hippocampus and found a 40% deficit in the ability of the brain to make new memories without sleep. In addition, scientists working with rats have found that depriving the brain of sleep stops the cells within the hippocampus’ memory structure from forming strong connections. Notably, it doesn’t take an entire night of sleep deprivation to produce these types of impediments—selective deprivation of deep, non-REM sleep in humans can produce the same effects.

Research has shown that during the deepest stage of deep, non-REM sleep, powerful brainwaves combine to act like a transfer mechanism. Wanting to know even more about how learning capacity and ability change across a waking day and how sleep modifies or restores that, Matt and his team designed a new study on daytime naps. They found that staying awake throughout the day resulted in a progressive decline in learning capacity, while those who took a ninety-minute nap showed no such decline. In fact, their capacity to memorize facts increased after that nap, showing a 20% learning advantage. This illustrates further that, without sufficient sleep, the brain is like a waterlogged sponge, our memory circuits saturated with memories so that we can no longer absorb new information and make new memories effectively.

Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.

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