Scientists unlock the secrets of sleep

This article has been corrected. You may view this article’s correction here.

In literature, sleep and dreams are often regarded as the frontiers of human understanding, containing memories of the past and portents of the future.

While the true meaning of dreams may long remain hidden, Yale professors from a variety of disciplines are researching what happens to our bodies and our minds while we sleep and dream. Their discoveries are not only enhancing scientific understanding of human development, but are also improving the quality of life for those coping with a variety of medical conditions.

Although commonly associated with the interpretation of dreams, the modern science of psychology has largely left behind its Freudian origins.

“Freud was big on dreams, but they don’t take Freud’s theory that seriously any more in psychology, and psychoanalysis isn’t that major of a theory in our field any more,” Psychology Director of Undergraduate Studies Woo-Kyoung Ahn said.

Part of the issue, according to Marvin Chin, who teaches “Introduction to Psychology,” is the absence of the scientific method from Freud’s work — many of his theories have been rejected by modern psychology because they were too subjective and could not be tested through experimentation.

“People do widely admire Freud for pointing out that there are a lot of unconscious processes important to human behavior, but the analysis of dreams, or psychoanalysis, is not considered to be a valid scientific way to understand these unconscious processes,” Chin said. “It’s too subjective. Freud could interpret a dream any way he wanted to, but another person could interpret it a different way, and there’s no way of telling who’s right and who’s wrong.”

Despite the flaws in early theories, psychologists have not left behind the question of what goes on in our heads while we sleep. They simply approach it in different ways — measuring sleep with electroencephalograms, which monitor brain waves, and other equipment to form a physiological picture of dreaming.

Using these modern instruments, researchers have discovered that infants dream far more than adult humans. Chin said this observation could be construed to suggest that dreaming is somehow tied to the rapid nervous system development that occurs in newborns.

Studies also suggest that dreaming helps consolidate memories and store them for long-term use.

Researchers at the Massachusetts Institute of Technology have shed new light on the nature of human dreams by examining those of animals, which can be manipulated more easily than human subjects, Chin said. By monitoring the activity in rats’ brains as they ran a maze, scientists were able to determine what rat brain patterns corresponded to different points in the maze. Subsequently monitoring these rats as they dreamed, scientists saw similar patterns arise.

“Basically, they’re dreaming of running around in mazes,” Chin said.

The patterns correlated so precisely that scientists were able to determine exactly where in the maze the rat dreamed it was.

While most find sleep to be a peaceful escape, for some, nightmares about the daily rat race are the least of their concerns. Severe sleep disorders can cause individuals to awaken more tired than they were before going to bed.

The Yale Center for Sleep Medicine deals primarily in researching and treating such medical conditions. The center places particular importance on sleep apnea, a disorder in which patients effectively suffocate themselves while asleep.

Sleep apnea arises partially from the relaxation of the body’s muscles during sleep. Once a particularly deep stage of sleep, called REM sleep, is reached, the body loses all muscle tone. This prevents sleepers from acting out their dreams, which also occur during REM sleep, but can prove dangerous to some individuals.

“What happens during sleep is that patients, while their muscle tone decreases, are trying to breathe … but because of the more collapsible upper airway, the airway starts to partially or entirely close up, so airflow cannot get down into the lungs,” Dr. Klar Yaggi of the Center for Sleep Medicine said. “That happens over and over throughout the night, sometimes on the order of 60 to 100 times an hour during sleep. Patients don’t get very consolidated sleep and, thus, experience a lot of symptoms of excessive daytime sleepiness.”

Sleep apnea has been linked to a variety of factors, several of which are controllable. Weight has a significant influence, since the disorder can only affect those whose necks are heavy enough to collapse the airway when muscles relax.

“We mainly see adults, but sleep apnea is also a problem in children, especially with the increasing rates of obesity that are also touching the pediatric [community],” Yaggi said. “There is an interesting association between sleep apnea in children and attention deficient and hyperactivity disorder. Children, when they become sleep deprived, tend to experience attention deficits and behavioral problems related to experiencing sleepiness during the daytime.”

Although sleep apnea is dangerous by itself, Yaggi said it can also lead to cardiovascular complications later in life. He said apnea can cause high blood pressure and is associated with strokes and congestive heart failure. According to a recently-completed study by the Center for Sleep Medicine, people with sleep apnea are two to three times more likely to have a fatal heart attack or stroke than those without the condition.

While Yaggi and his colleagues are focusing on helping unhealthy sleepers, other members of the University faculty, including Dr. Scott Rivkees, are more interested in how to promote healthy sleep cycles in children.

Rivkees, a professor of pediatrics, has spent the last 10 years studying circadian rhythms — 24-hour patterns, such as the sleep-wake cycle, that govern the human body. His work has focused on how these rhythms develop in young children, particularly newborns.

Circadian rhythms are kept in phase with the external world, most specifically the cycle of day and night, by information relayed from the eye to the brain. This can present a problem for premature babies, Rivkees said, who must be kept in neonatal intensive care units until they can survive on their own. These newborns are kept in constant dim light and thus cannot establish rhythms in sync with night and day.

Rivkees’ studies found that children exposed to natural light cycles while in intensive care often develop natural sleep-wake cycles as much as a month before children placed in a standard dim-lighting intensive care facility. Adjusting the lighting in neonatal intensive care wards could go a long way towards giving the 10 percent of babies born prematurely a more normal infancy, he said.

“I’ve always had a long-standing interest in circadian biology, and I have always been surprised at the lack of consideration towards it,” Rivkees said. “It’s not clear — why are we raising children in constant darkness, which is something that is completely different from what would happen in the natural situation?”

Cartoon Sci/Tech
Doug D'Agati
Cartoon Sci/Tech

Comments