I feel tired? Here’s How Your Brain’s ‘Hourglass’ Controls Your Need to Sleep – New Research

by Lucas B KronAnd Oxford university; Vladislav VyazovskyAnd Oxford university, And Zoltan MolnarAnd Oxford university

Nobody can stay awake forever. When we are awake, our need for sleep gradually increases. If we deprive ourselves of sleep, brain functions – such as attention or judgment – are disrupted, and sleep becomes irresistible. No matter if we’re on the couch or at work – if we ignore our need for sleep, we end up crashing.

Although sleep is vital, it is not yet known which brain structure tells us when we feel tired. but Our latest study He showed in lab mice that the cerebral cortex, which is responsible for more complex brain functions — including cognition, language, thought and episodic memory — helps us track our need for sleep.

clock and hourglass

To ensure that we get enough sleep, our brain uses two tools: a clock and an hourglass. Our biological clock helps us maintain a 24-hour rhythm. control it acclimatization nucleus, which is a small area deep in our brain. This coordinates the rhythms of different organs, helping us to fall asleep at night and wake up in the morning.

But our biological clock is only a guide – it is not the main regulator of sleep. Instead, the brain uses the “hourglass” to keep track of the accumulated amount of sleep we’ve had. This hourglass slowly empties while we’re awake and refills while we sleep. This is why we are able to stay awake longer when we need to, and make up for this lack of sleep later by napping or sleeping longer the next night.

While we have a good understanding of the hourly location, the location of the hourglass is still up for debate. About 100 years ago, the Viennese neurologist Konstantin von Economou believed that the anterior hypothalamus, the junction of the forebrain, and the brainstem – the area in front of where eye movements begin – were essential to the state of wakefulness and sleep. Since then, many centers that can switch the brain between wakefulness and sleep recognized – But the timekeeping center is not found.

Some researchers have suggested that the brain doesn’t measure the time we’ve spent awake – it tracks How hard is the brain working while we are awakeand adjusts the amount of sleep we need accordingly. Research supporting this theory has found that individual domains of The crust can go off for a short time When tired, even when the rest of the brain is awake. This temporary shutdown of individual brain regions is called ‘local sleep’ and is thought to be a mechanism Allows brain cells to recover. While a person may not notice it, such a local shutdown can happen It profoundly affects someone’s performance – For example while driving a car.

But our brain would be very inefficient if individual parts of the cerebral cortex often went into local sleep whenever they felt they needed to. For this reason, it is believed that the cerebral cortex may not only generate local sleep, but also activate the main sleep centers.


To test whether the cerebral cortex is actually responsible for tracking our need for sleep, we disrupted a group of cells in the cortex of mice. This prevented their peel from Refers to other neurons.

We noticed that these mice stayed awake for three hours longer each day than the other mice, and were unable to sleep properly when they were kept awake beyond their usual bedtime. But while the hourglass seemed to run slower in these mice, the clock did not change. Therefore, even when mice were placed in complete darkness for a few days, they maintained their usual sleep-wake rhythm in the same way as mice with normal cortex.

But while we’ve shown that the cerebral cortex plays an important role in regulating sleep, we still don’t know why this specific area of ​​the brain regulates our need for sleep.

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The cortex is one of the most complex areas of the brain. It can permanently reset its structural connections to store new memories and eliminate old ones, and it takes a great deal of energy to process information. While in principle any neuron may have a mechanism that allows it to shut down before it is damaged by overuse, the cortex may be the area most in need of sleep and first tells us when we are tired and how much sleep we need.

If the cerebral cortex plays a large role in making us tired, can we somehow manipulate the cortex and alter our need for sleep? In recent years, several techniques have been developed to stimulate the brain from the outside using electrode pads placed on the head or through magnetic coils placed over the skull. Both methods generate electrical currents that modulate the electrical signals that neurons use to communicate with each other. This could thus allow researchers to modify brain activity in a specific area – such as the cortex.

In fact, at least one of these techniques appears to be temporary Makes the brain more awake and can reduce the amount of sleep The next night, about 25 minutes. So it seems possible that, in the near future, the cortex could become the target of similar approaches to dealing with our need for sleep.

Even if researchers can find ways to do this, that doesn’t necessarily mean you’ll be able to sleep less and do as much — or more — than you do now. Sleep suppression can be dangerous, as sleep serves many essential things, but is still poorly understood, Functions in our body and brain Like processing memory, making sure the immune system and metabolism are working properly. But for many of us who struggle to feel tired and fall asleep, manipulating the cortex can become a way to induce sleep when we struggle to fall asleep.Conversation

Lucas B KronPhD researcher in neuroscience, Oxford university; Vladislav Vyazovsky, associate professor of neuroscience, Oxford university, And Zoltan MolnarProfessor of Developmental Neuroscience, Oxford university

This article has been republished from Conversation Under Creative Commons License. Read the original article.

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