Have you ever stayed up all night cramming for a test, only to forget the answer to every question? It turns out you're just overtired. The good news is science might have found a way to retrieve lost memory.
Why Sleep Deprivation Affects Memory
An all-night study or work session may feel like a good idea at the time, but your brain depends on those hours of sleep to perform at its best. Sleep helps you pay attention, process facts, and make memories you can draw on later.
Scientists don't know everything about how sleep helps us make memories, but they know it works like cleaning a room. When we sleep, our brains scan through the memories we've formed and discard those that aren't important — like a truck that drove by while you were studying or the squirrel you saw in the yard. Meanwhile, it holds onto the memories you'll need later - and creates pathways so you can get to them.
Not getting enough sleep interferes with this process. Your brain doesn't have time to make new pathways for the information you need to remember, so you can't get to that information when you need it. It also can't connect your new memories to old memories—a cognitive process that helps us remember more effectively.
Luckily, Dutch researchers have learned that those memories aren't lost—just hiding in the brain, waiting for us to find them.
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A Memory Flashlight
The study to find lost memories started with neuroscientist Robbert Havekes, an associate professor at the University of Groningen in the Netherlands. In a study published in the journal Current Biology in December 2022, he and his team used genetic science to grow a light-sensitive protein in the brains of mice.
They grew those proteins in brain cells that became active when the mice learned something. Those cells were located in the hippocampus, an area of the brain that stores spatial information and facts. The proteins would allow the research team to retrieve lost memory by “shining light” on those cells.
Learning and Forgetting
To test the effects of sleep deprivation on learning, the scientists put the mice through a spatial learning task. First, they kept some mice awake before the task and let the other mice sleep normally. Then, all the mice received the task of learning the location of multiple objects.
A few days later, the scientists hid the same objects but moved one thing to a different location. The mice who had been sleep-deprived didn't seem to remember what they'd learned. They didn't notice that one object was in a different place. The scientists took this as a sign that they'd forgotten the original object locations.
Reactivating the Memory
The scientists believed they could help the mice recall what they had learned. So they shone a light on the brain cells that included the unique proteins, which seemed to reactivate the memory. When the scientists returned the sleep-deprived learners to the task, the mice remembered the objects' original location.
The scientists saw that sleep deprivation hadn't prevented the mice from making memories. Instead, it had caused their brains to forget how to find them!
They also realized that since the memories were retrievable, there might be a way to get them back without special cells.
A Memory Drug?
The scientists knew that an asthma drug called roflumilast also activates the same pathway. So to test their theory, they gave the medicine to a group of sleep-deprived mice before their second object location test.
The drug had the same effect as the light activation. They remembered where the objects had been when they learned their location.
Will it Work in Humans?
It is, however, important to note that mice are not the perfect models for testing drugs for use in humans because although we have identical genes, those genes are used in different ways in mice and humans and this means that the drugs, a lot of the time, react differently in our body systems than they do in mice. Furthermore, research has shown that despite looking safe and effective in animal tests, more than 90% of medicines end up being unsafe in humans.
Hence, scientists don't yet know if they can retrieve lost memory in humans as they have in mice. However, they know that the roflumilast drug already has approval for human use. Also, it can enter the brain, which many drugs can't.
Dr. Havekes believes there could be many applications for this and similar drugs. For example, he says, it could be helpful for people with Alzheimer's disease and other age-related memory issues.
Lost Memory Retrieval: The Next Steps
To make clinical progress in retrieving lost memory, scientists need to know whether they can replicate this process in humans. To do that, they need to find out why sleep deprivation hides those memories and how the drug brings them back.
Studies like these need human participants to make exciting clinical discoveries. For information about current recruiting studies, Sign Up for our Free Pulse Newsletter today!