The phrase, "dreams are made for children," might have taken on new meaning, based on a study at Washington State University Spokane. The study, published in Science Advances and reported in Medical News Today, says that rapid eye movement (REM) sleep - where dreams take place -- "actively converts waking experiences into lasting memories and abilities in young brains...and calls into question the increasing use of REM-disrupting medications and antidepressants" (http://www.medicalnewstoday.com/releases/296333.php).
REM, one of the five stages of sleep that most people experience nightly, entails quick, random movements of the eyes and paralysis of the muscles. Time spent in REM sleep varies with age, normally making up about 20 to 25 percent of an adult human's total time spent asleep (90 to 120 minutes) and more than half of an infant's (http://www.medicalnewstoday.com/articles/247927.php).
While scientists have known that infant animals spend much of their early life in REM sleep, little was understood about the mechanics of REM's ability to change or recombine memories, according to Professor of Medical Sciences Marcos Frank. In the study, which was funded by the National Institutes of Health, Frank and his team documented the effects of sleep on vision development in young animals. They discovered that brain circuits change in the visual cortex when animals explore their environment, but that REM sleep is needed to make those changes "stick." The changes are cemented by ERK, an enzyme triggered only during REM sleep.
According to Frank, "REM sleep acts like the chemical developer in old-fashioned photography to make traces of experience more permanent and focused in the brain. Experience is fragile. These traces tend to vanish without REM sleep and the brain basically forgets what it saw."
Young brains, says Frank, "go through critical periods of plasticity" -- or remodeling - at which time vision, speech, language, motor skills, social skills and other higher cognitive functions develop. During these periods, REM sleep helps growing brains to adjust their neuronal connections to match the input received from their environment.
According to Frank, brain activity patterns occurring in REM sleep are similar to those when awake, "as if the neurons were dreaming of their waking experience. Until now, there has not been strong evidence to show that waking experience reappears during REM sleep." He believes that "REM sleep may be important for the development of other parts of the brain beyond the visual cortex and its effects may continue throughout a lifetime."
Frank thinks that the study "has big implications for our understanding of sleep in children." Not only does the amount of sleep a child gets affect his or her ability to do well in school, but the specific amount of sleep changes over time. In addition, he is concerned about what Ritalin for attention deficit disorder, antidepressants and other drugs are doing to developing brains in both the short and long term. He concluded, "Almost all of these compounds can potentially suppress sleep and REM sleep in particular. REM sleep is very fragile -- it can be inhibited by drugs very easily."
