Study suggests REM sleep helps developmental processes by strengthening neuronal connections associated with stimuli from environment.

Professor of Medical Sciences Marcos Frank, along with other scientists from the Washington State University Spokane have discovered that Rapid Eye Movement (REM) sleep is essential for the brain development in young animals and children.

Published in Science Advances, the finding aim to broaden our understanding of children’s sleeping patterns and needs, and also flags the consequences of using of REM-disrupting medication, such as antidepressants and stimulants.

REM And Remembering Experiences

It has long been known that animal infants spend most of their early life in REM sleep. However, little information was available on how REM sleep could change or make associations among memories and experiences. Frank and colleagues have provided new insights on how sleep effects vision development in infantile animals. They found that certain neurological circuits in the visual cortex change as new images and visual stimuli are experienced. More importantly, REM sleep is what locks and maintains these changes.

The scientists demonstrated that an enzyme known as ERK – activated during REM sleep – is what makes these changes stick, establishing that REM sleep dynamically converts waking experiences into long-lasting memories.

Frank further explained that young brains of both, animals and children tend to experience phases of remodeling, where vision, language, speech, motor and social skills are developed. The findings of this study suggest that REM sleep helps these developmental processes by strengthening neuronal connections associated with stimuli from the environment.

REM And Visual Development

Frank stated in the 1960s, surgeons observed that late removal of congenital cataracts in children caused severe complications, such as double vision and loss of eye alignment.

“The visual cortex is very sensitive to information it is receiving and there are critical periods for its development,” he explained. “If vision is blocked at these stages, then problems result.”

Researchers used a model based on these findings to determine whether REM had any specific role in the development of vision. Animal models were made to wear a patch over one eye while their brain activity was monitored during sleeping and wakefulness. When the animals were in REM sleep, they were gently awakened by tapping their enclosures – controls were awakened when they were in non-REM sleep.

Results revealed that the animals that did not get sufficient REM sleep did not develop normal vision. Frank established that a lack of REM sleep did not allow permanent changes in the visual cortex and also inhibited the activation of ERK enzyme.  

REM Sleep And Overall Brain Development

Frank and his team were also surprised to discover that brain activity during REM sleep had patterns similar to those occurring during wakefulness.

“It’s as if the neurons were dreaming of their waking experience,” he stated. This is the first study to have established evidence that waking experiences reappear during REM sleep. Frank added that REM sleep might also play an important role in developing other areas of the brain, and this may continue throughout a person’s life.

Impact Of Findings

Frank believes that the study has huge implications understanding sleep in children. He says that the findings can help fully explain how and why specific amounts of sleep are essential for learning and performance. The detrimental effects of restricting sleep in children can also be observed.  

Moreover, practices of prescribing antidepressants and other medications to children that contain REM-disrupting or suppressing compounds is becoming fairly common. Frank highlighted the lack of pre-clinical research regarding the effects of using these drugs, and how they might affect the developing mind of a child, both short and long-term. Hence, the study could open new avenues into clinical research and drug improvement.