An experiment manages to simulate the benefits of a nap without sleeping

Research points to the future possibility of a therapy to correct the damage caused by insomnia

That sleep is a primary need, like drinking and eating, is something we have all experienced after a bad night’s sleep, and what happens in extreme situations is known from unfortunate cases such as that of families suffering from a lethal form of hereditary insomnia . However, why we need to sleep is a mystery that has not yet been fully solved. A team of researchers has managed to simulate one of the benefits of sleep through brain stimulation, which points to the future possibility of a therapy to correct the damage caused by insomnia, but also to something else: will we ever have a device that allows us to enjoy the rest of sleep without needing to sleep?

Restful sleep is the most classic view of why we need to sleep, and it is true that during sleep the body enters maintenance mode: energy consumption is reduced and the restorative functions of the metabolism are favoured. But while some of these benefits can be obtained with simple rest, the brain, on the other hand, needs sleep: as the psychiatrist Allan Hobson wrote, “sleep is of the brain, by the brain and for the brain.” Although our thinking organ also reduces its activity compared to wakefulness, it is far from being off ; it is the brain processes during sleep that motivate the need to sleep and are the focus of most research.

Some of the brain effects of sleep are well known. Its role in memory consolidation is widely accepted, and it has been suggested that sleep enables neuronal repair. In 2013, researchers at the University of Rochester Medical Center in New York discovered that in mice, sleep narrows the space between neurons, allowing in fluid that bathes the brain, thereby flushing out toxic metabolic waste such as the amyloid beta protein implicated in Alzheimer’s. A commentary in Science magazine compared it to taking out the trash. The finding, which was among Science ‘s 10 most important findings of the year , supports the idea that proper sleep helps prevent neurodegenerative diseases.

Sync to sleep more

In the new work, also published in Science , researchers from Rice University, Weill Cornell Medical College and the Houston Methodist Research Institute — all in the US — studied non-rapid eye movement (NREM) sleep, the state that repeatedly alternates with REM sleep throughout the night and whose role in maintaining mental functions is less well understood. Since NREM sleep precedes REM, this state is typical of a short nap.

The authors studied neuronal activity in the brains of a group of macaques during and after a 30-minute nap, as well as the monkeys’ ability to solve a task consisting of identifying identical images with different orientations. “During sleep, we observed an increase in low-frequency delta wave activity and synchronized firing of neurons in different cortical regions,” explains the study’s first author, Natasha Kharas. These slow brain waves are characteristic of NREM sleep.

According to Kharas, this synchronization of neurons during sleep prepares the brain to work better when waking up: “After sleep, however, neuronal activity became more asynchronous than before sleep, allowing neurons to fire more independently. This change led to greater precision in processing information and performing visual tasks.” Therefore, it could be said that sleep, in this case a nap, clears and sharpens the mind to improve performance.

The researchers then tested what would happen if they transmitted impulses through brain electrodes to the macaques while they were awake to simulate the slow-wave activity of sleep. They found that this artificial stimulation was enough to achieve the desynchronization effect and to obtain performance on the task that was similar to that observed after a nap. According to the director of the study, Valentin Dragoi, “this finding is significant because it suggests that some of the restorative and performance-enhancing effects of sleep could be obtained without the need for sleep.”

Sleep without sleeping

Dragoi points to the potential applications of his results: “We plan to carry out clinical trials on human patients suffering from sleep disorders, stimulating different parts of their brain with delta electrical waves to alleviate the deficiencies in memory and cognitive performance due to lack of sleep.” But the researcher also believes that the scope of this discovery could be greater: “We want to examine whether we can emulate the beneficial effects of sleep without sleep, which would be widely beneficial in a variety of applications in healthy people.”

However, in order for humans to be able to enjoy the benefits of a sleep simulator, scientists will first need to find a way to deliver this brain stimulation externally, without implanting electrodes in the brain , as is the case with macaques. “There are great possibilities,” says Dragoi. “The invasive electrical stimulation was applied superficially, in the upper layers of the cortex, which encourages us to explore noninvasive electrical stimulation protocols by varying the location in the cortex, the intensity of the current and the area of ​​the surface to be stimulated in order to obtain effects comparable to those induced by invasive stimulation.”

All of the above refers to NREM sleep, but if we are to ever have technology that truly offers us the full rest and restorative benefits of sleepless sleep, it will also be necessary to simulate REM sleep, the state in which we dream most vividly. Dragoi is optimistic about expanding his studies to the entire sleep cycle: “This will require further experiments to examine the role of other sleep states and in particular the function of REM sleep, and to find specific ways to substitute for it using targeted electrical stimulation.” For now, sleepless sleep remains just a dream.