Rapid eye movements during sleep are not random

A group of researchers from the University of California at San Francisco conducted the first study that proved that rapid eye movements during sleep are not random.

The study looked at “head direction” cells in the brains of mice, which are neurons that fire in the brain depending on where the animal is heading. The researchers then compared the sleeping mouse’s direction of movement with the movements of its eyes. The cells found were aligned during REM sleep, just as it happens when the mouse is awake and moving around. This led scientists to believe that people move their eyes during sleep to “look around in the world of dreams.”

Rapid eye movement (REM) during sleep has baffled scientists ever since it was first associated with dreams in 1953, but a new study has shown that these movements are not random.

Interestingly, the eyes move during sleep in exactly the same way as during wakefulness.

What is REM sleep?

REM sleep – or “rapid eye movement” – is one of several sleep cycles that the body goes through each night.

It starts about 90 minutes after falling asleep. Longer periods of REM sleep occur with each subsequent cycle. However, this scene is characterized by more than just rapid eye movements. REM sleep also leads to increased heart rate, paralysis of the limbs, waking-style brainwaves, and dreaming.

During this phase, brain wave patterns are similar to those seen during wakefulness, during which people experience dreams.

REM was first identified by Eugene Aserinski, who is also credited with creating the first sleep laboratory to detect “fast, jerky, binocularly symmetrical movements.”

This idea, however, was just a hypothesis, but the new study is the first to provide strong evidence supporting Acerinksy’s theory.

Massimo Scanziani, senior author of the study, said: “We have shown that these eye movements are not random. They coordinate with what happens in the virtual world of the mouse’s dreams. This work gives us insight into ongoing cognitive processes in the sleeping brain and at the same time solves a mystery that has piqued the curiosity of scientists for decades.”

Scanziani’s team found that the same areas of the brain coordinate their actions during both sleep and wakefulness, supporting the idea that dreams are a way of integrating information gathered during the day.

How these areas of the brain work together to develop this ability to generate is a mystery that Scanziani plans to unravel next.

“It is important to understand how the brain renews itself based on experience. Understanding the mechanisms that allow us to coordinate so many different parts of the brain during sleep will give us insight into how these experiences become part of our individual understanding of what the world is and how it works,” he said.

Christina DENISYUK.

Photo: Alamy Stock Photo