Want stronger memories? Science says sleep more, avoid sedatives

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Want stronger memories? Science says sleep more, avoid sedatives
WATCH: Scientists say the "scaling down" or "smart forgetting" process is necessary for our brains – Feb 3, 2017

Are you taking sleep aids to help fall asleep faster? It may be inhibiting your brain from processing important information and forming lasting memories, according to two new studies published in the journal Science.

The separate studies suggest that the purpose of sleep is actually to forget the noise we pick up during the day (like where we parked our car). The research suggest, forgetting that noise helps us reinforce stronger memories for important information (such as knowledge we require for our jobs), or, “smart forgetting.”

The research

Long-held theories within the scientific community of the purpose of sleep are that it is either for restorative purposes or for information processing.

Researchers from the University of Wisconsin-Madison and Johns Hopkins University (JHU) have published separate papers supporting the information processing hypothesis, finding that synapses in our brains “scale down” or prune less important information during sleep.

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“When we are awake we are always learning something new, always trying to adapt to the environment and change the connections in our brains because of this plasticity,” said University of Madison-Wisconsin’s Chiara Cirelli.

“This change usually leads to an increase and strengthening of these connections, which is good up to a certain point because you need to renormalize those connections. That’s what we think sleep does in a very smart and balanced way.”

The JHU researchers looked specifically at the role of the protein Homer1a in sleep regulation. They found that the protein shifts the communication between neurons to synapse pruning.

They observed that sleeping mice had 250 per cent more Homer1a compared to mice which were awake. They also observed that the protein was elevated in sleep-deprived mice, indicating that our brains will eventually kick start this pruning process because it’s necessary.

“It helps to consolidate the memories by basically subtracting the noise; it helps the memories emerge from the chaos of all these things we have in our heads,” JHU post-doctoral fellow Graham Diering told Global News. “But it also wipes the slate clean which makes it easier to learn new things when you wake up the next day.”

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At the University of Wisconsin-Madison, Cirelli and Giulio Tononi have been studying, for over a decade, whether brain synapses weaken and shrink during sleep, compared to when we are awake. They looked at two specific areas in the cerebral cortex in a mouse’s brain and observed synapses shrink nearly 20 per cent during sleep.

“We know that sleep brings about a lot of good things from a behavioural standpoint… [such as] forgetting many details that are irrelevant, which is crucial, because our brain is very good at remembering stuff. From our studies, we started suggesting some mechanisms on the neuronal level on how this happens,” said Cirelli.

The potential side-effect of sleep aids

Although further research needs to be conducted, Diering and Cirelli both said their findings imply that sedatives are working against the smart forgetting process.

Diering, who is originally from Vancouver, B.C., described popular sleep aids as a “sledgehammer” to the brain that instructs it to shut down. The drugs work by enhancing a neurotransmitter that inhibits all brain activity, thus helping patients fall asleep faster. But because this neurotransmitter is a general inhibitor and the drugs don’t target the specific sleep pathways, it doesn’t allow scaling down to happen.

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So what happens when we don’t give our brains the chance to scale down?

In experiments, Diering found that memories and information became fuzzy and lost specificity. He also has a theory that the pruning that occurs while you’re sleep-deprived won’t be as refined and instead just wipe everything clean, making newly learned information virtually obsolete.

“This is of course ancient wisdom, right? Cramming for an exam is not a very effective way to learn anything,” he said.

“Now that we’re looking under the hood in the brain and starting to see the pieces – like this Homer1a protein – once we start to understand those moving parts that control sleep or allow sleep, now we can start to ask where would be the best place to [target in our brains to] make drugs that would help us sleep better.”

Sleep remains a mystery for scientists. Cirelli said they hope to expand their research methodology to other parts of the brain and see if similar synapse size changes occur throughout our brains.

“Sleep does something very powerful to our brains. Twenty per cent change in size in synapses in just six, seven, hours is an astounding effect! So we should be very protective and respect our sleep.”

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