What do scientists know about dreams?
And what’s still a matter of fantasy and folklore?
Our experts help us find out.
First, science. People generally cycle through four stages of sleep several times during the night, with the last phase, known as rapid eye movement or REM sleep, getting longer each time around. Dreams generally occur during REM sleep; we can even imagine people’s eyes are moving to “watch” their dreams. Yet despite all the time we spend sleeping and dreaming, scientists know relatively little about sleep and dreams, says Karen D. Sullivan, Ph.D., ABPP, board-certified neuropsychologist and owner of Pinehurst Neuropsychology Brain & Memory Clinic.
“Each [stage of sleep] performs unique restorative functions across all systems of the body, with a particular focus on cellular, immune, cognitive and psychological health,” she explains. “REM sleep specifically is thought to be essential for two functions: first, the formation of new memories, especially procedural memory… and second, a type of deep cleaning, where the immune system and brain ‘cooperate’ to remove waste products that build up during
the day.”
One misconception about dreams is that they all occur during REM sleep; Sullivan explains that they most frequently occur then, but not always. And scientists have not yet discovered the algorithm that determines how the brain turns housekeeping and memory formation into engaging stories (or horrific nightmares).
“The exact purpose of dreaming is not known,” Dr. Sullivan says. “It is likely a method of emotional processing, particularly of life experiences that are distressing to us in some way. Our hippocampus, the learning and memory centers of the brain, and frontal lobes, essentially ‘replay’ the day’s events all night long. The purpose is to compare notes from our day against the backdrop of total life experience with a specific eye on discrepancies. If something surprising or unexpected happens, it gets reviewed, or processed, until the lesson is learned.”
The process, Dr. Sullivan says, is the brain’s way of reconciling an unexpected or traumatic event with the larger backdrop of our memories. It’s an attempt at making meaning.
“Through this ‘replaying’ process, we decide what can be forgotten and what should be moved into long-term storage in the cerebral cortex,” she says.
Yes, some dreams do seem like replays and sorting tools. For instance, when I dream about real people and events, I can guess that maybe I’m sorting out memories. But some other dreams seem pretty fantastic. I’m certainly not the only one who’s been pursued by dragons or witches in dreams, or received gifts from beautiful fairies. Are those memories, too? Where do dream stories and people actually come from? I ask Sullivan for the academic perspective on dream meanings.
“Dream interpretation comes down to two things for me: symbols of the personal and collective unconscious,” she answers. “The themes and images of dreams are not random; they are symbolic and related to both our unique, personal life history, and to the history of humans across generations and cultures.”
She refers me to Carl Jung, one of the creators of a school of psychology known as depth psychology, which holds that people have an unconscious, spiritual aspect that informs our lives. Jung also taught that people’s unconscious life is partly shared or collective, a grammar of universal symbols out of which we create meaning.
“Carl Jung taught us that there are many dream symbols that are universal and occur in people living in all types of life circumstances, such as being lost, unprepared for responsibility or threatened by forces of the natural world,” she says.
This fascinates me. If the symbolic language of dreams is universal, do our dreams know more than we do? And can they affect us—or we, them?
Dream Mastery
It’s hard, but not impossible, to manipulate one’s dreams. Some medications, for instance, produce good or bad dreams. Dementia patients who take donepezil may experience nightmares, Sullivan says. And personally, I find one happy side effect of allergy season is the delicious flying dreams I get while taking Montelukast sodium. On the other hand, people who suffer from nightmares, such as veterans with post-traumatic stress disorder, may experience relief from prazosin, which is also a blood-pressure medication, Sullivan says.
Then, there are people who believe they can direct their dreams, re-writing unpleasant scripts, or just planning a happy adventure. I remember my granny putting me to sleep by telling me a story about a unicorn or mermaid. “Now fall asleep to see what happens next,” she would say, tucking me in. I don’t remember whether it worked, though! But other groups claim to teach directed or “lucid” dreaming.
Dream Awake
Like the ballet by the same name, dreams are when some of us feel the most awake: colors are brighter. People and places seem more real. Others of us never remember dreams or only recall traces. Whether they feel true or, well, dreamy, dreams are typically composed of things that are more the purvey of art, myth, and religion than of science: stories. Here are a few ways humans have understood dream-as-story.
• Divine messages; for example, the God of the Christian Bible directs Joseph to take his family and flee from Herod.
• Predictions; for example, Harriet Tubman said that she previously dreamed much of what later happened to her as she began to rescue slaves from the South.
• Creation; for example, in the Abenaki creation story, the Creator dreams of all the animals, and when he awakes he finds that they have come into existence.
How do you interpret your dreams? Through the lens of biology, psychology, or myth? Whatever your approach, there’s probably more to your dreams than meets the eye.
Toothy Sleep Troubles
When your emotions seep through into your sleep, you may find help in an unexpected place: your dentist’s office.
“There are two main issues connecting teeth and sleep,” says Laura Wellener, DDS. “One is sleep apnea and the other is bruxism, or teeth grinding.”
Sleep apnea, of course, is the condition in which people periodically stop breathing during sleep. Often caused by excess weight, sleep apnea may also cause snoring, snorting, and — since the body realizes there’s something wrong when it doesn’t get enough oxygen — stress. That stress is what may alert the dentist.
“When people with sleep apnea are sleeping, the excess tissue in the back of their throat collapses, and they may wake to gasp for air,” Wellener explains. “We’re now finding that those people clench and grind their teeth, possibly because the brain signals the jaw muscle to clench up as the airway collapses. The other side of that is that when there is not enough oxygen in the bloodstream, the body has a stress response.”
And stress, Wellener says, is one common cause of tooth-grinding. The cycle becomes vicious when bruxism interrupts the sleep cycle, leading to interruption of slow-wave “delta” sleep and consequently to stress and depression.
“If you grind or clench your teeth [you won’t wake] up refreshed,” Wellener says. “When you grind your teeth you won’t go into the delta phase, or deep phase, of sleep. In the delta phase, the muscles relax, and they won’t get there if the jaw is tensing up.”
As well as stress, missing teeth or poor dental alignment can lead to tooth-grinding, Dr. Wellener says. A dental visit can lead to a diagnosis of bruxism based on signs of eroded enamel or unexplained cracks or chips. If you have jaw and muscle soreness around the face, or unexplained tooth pain, be sure to mention those signs to a dentist.
“If you’re just grinding your teeth, a nightguard is a treatment,” says Wellener, who swears by hers. “They decrease the force when you grind, helping you relax your jaw muscles. That should improve sleep quality.”
And if you have problems with grinding your teeth, your dentist may be your first line of defense against sleep apnea. With a few key questions, he or she can point you to a sleep study and a long-term plan for better sleep.