Hall & Oates had their dreams come true. Leonardo DiCaprio tried to steal corporate secrets by invading dreams in the movie “Inception.” Even the most acclaimed Shakespearean soliloquy mines this subconscious territory, although Hamlet was thinking of the deepest of sleeps when he wondered if he could, perchance, finally dream.

Marketers tout a sweet dream when they sell comfy pillows, while just about everyone views their highest aspirations as metaphorical dreams. The dream state seems to be always on our minds.

Still, even though dreaming has a central place in our lives, those who study oneirology, or the science of dreams, acknowledge that people’s interpretations of their dreams, as nonsensical and weird as those dreams can be, are in some ways just as revelatory as the scientific research of why we dream in the first place.

In other words, a dream about forgetting your high school locker combination decades after you have graduated could, in fact, be your brain’s way of working out a recent or impending stressful event in reality. It’s your mind clearing your deck. If you also want to interpret the dream as a reminder to not forget the glory days of your teenage years, go right ahead. You’re not necessarily wrong. The reasoning behind dreaming is elusive and open to all sorts of theories.

“Why do we dream? The precise answer is we don’t know,” said Micah Sadigh, a professor and the chair of psychology at Cedar Crest College in Allentown, Pennsylvania. “It’s not that simple. You’d figure there must be a single answer, but it’s so complex and so many different things happen that it would be difficult to capture all of those in one statement.”

Dreams Offer Meaningful Clues

Indeed, as Sadigh suggests, it’s not that experts haven’t made progress in understanding dreams. It’s just that, like dreams themselves, the scientific and psychoanalytical components of our sleeping selves are multi-layered, complicated, involved and personal. After all, if the eminent psychologists Carl Jung and Sigmund Freud couldn’t concur on the underpinnings of dreams — a disagreement so severe that it ended their friendship — where does that leave the rest of us?

Freud and Jung both believed that dreams are the manifestation of our subconscious. Freud divided dreams into manifest content — conscious imaginings that the individual uses to disguise unacceptable feelings — and latent content, the “forbidden” stuff that is typically sexual and aggressive and tied to childhood fantasies. While Jung didn’t disagree that dreams were messages from the subconscious mind, he contended that our dreams went beyond illustrating internal conflicts. They also offer a remedy or cure for what’s bothering us. Maybe recurring dreams about the forgotten high school locker combination are telling us to look at a real-life stressful situation in a new way.

“One theory about dreaming is that it plays a significant role in preparing us for the next day,” Sadigh said. This is what neuroscientists call Threat Simulation Theory of Dreaming. It holds that by repeatedly simulating threats in our dreams, we better understand what could harm us. “As a culture, we pay little attention to our dreams, which is unfortunate because they can help us with problem solving,” Sadigh added.

Technology Is Slowly Opening the Curtain

Credit technology with allowing neuroscientists to see, more than ever, what’s going on in the mind. The couch of a disciple of Jung or Freud is still available to analyze dreams, but fMRIs, PET scans and high-density EEGs reveal how the brain works at night.

Such technology has enhanced research on lucid dreaming, the stage in which we realize we’re dreaming and sometimes can control what transpires. For instance, neuroscientists can measure the frequency with which patients have lucid dreams. For those who have persistent nightmares resulting from post-traumatic stress, Sadigh said, the ability to change the ending of those dreams can lead to significant psychological recovery.

The ability to control the ending of good dreams is one of slumber’s joys. This writer has willed his subconscious to hit a homerun or two when dreaming of playing for the Boston Red Sox. But the brain doesn’t always go along with such fanciful thinking.

“You have millions and millions of cells talking to one another to get to a dream scenario,” Sadigh said. “It’s not impossible but not always probable that we can (control) lucid dreaming. We need to respect the wisdom of the brain. It might be saying, ‘No, today you’re not playing for the Red Sox. This part of the brain has been taxed. I want you to work on these problems.’ It’s an ancient organ. We should trust it and be respectful.”

A Beatle Dreams of Yesterday

Not only can dreams spark our survival instinct to work out debilitating problems, Sadigh said, but they can also fuel creativity. An idea for a story, song, painting or other creative work can generate in a dream, he said. During sleep, the brain continues to think and often dream big.

Paul McCartney conceived two popular Beatles songs in his dreams: the melody to “Yesterday” and the lyrics of “Let It Be.” One morning in 1963, McCartney woke and hurried to a piano, where the sound of “Yesterday” came flowing from his fingertips. The lyrics didn’t come as quickly, though; for more than a year he used “scrambled eggs” as a placeholder in the chorus until he could get the words right.

Not long after, as McCartney explained to James Corden in “Carpool Karaoke,” his deceased mother, Mary, appeared to him in a dream, during a stressful time, and told him, “It’s going to be okay, just let it be.”

The Science of Dreams Still Confounds Experts

Sadigh points to how in 1953, scientists devoted a lot of attention to studying the link between rapid eye movement (REM) and dreams. Maybe too much attention, he said. “Dreaming is not just specific to REM; it also occurs in non-REM sleep. We’re dreaming throughout the night. But there are different qualities to REM and non-REM dreaming.”

Dreaming in early REM tends to have a puzzling quality or can be negative, Sadigh said. The more people can sleep each night, the better chance they’ll have of breaking through stressful REM cycles and moving onto the more coherent and relatively pleasant dreams of latter REM stages, he said. Eight hours of sleep should provide enough time to reach six REM cycles, he added.

Dreams do happen in non-REM sleeping. But here the region of the brain, the anterior cingulate cortex, is dormant, whereas it is active in REM sleep, Sadigh said. “We are puzzled trying to figure out things like that. It’s why one way of referring to REM and non-REM sleep is “paradoxical sleep.” They are different. Brain wave activity is more active and cardiovascular is more active” in REM sleep, he said.

Few will dispute that dreaming can be restorative and rejuvenating, a key to good mental health and a door to enhanced creativity and problem solving, but there are still many questions about how it all works. Despite the many advances in oneirology, the role of dreaming isn’t crystal clear.

“Dreaming is a very complex phenomenon that does different things,” Sadigh said. “If you were to deprive people of REM sleep, you do see them develop memory problems and have a diminished ability to recall things and consolidate memories. Where there is a deterioration in REM sleep, you see diminishment of memory, particularly in Alzheimer’s patients.”

Dreaming Can Be a Beautiful Dance

No two individuals are completely alike, of course, so the effects of dreaming differ from person to person. For instance, while achieving five or six REM cycles seems beneficial to most, there is concern that dreaming too much might be connected to poor mental health, Sadigh said.

For almost anyone, though, sleeping and dreaming should be viewed as a balance that requires not just our attention but our appreciation.

“The normal sleep architecture is a beautiful dance between the various stages of sleep…there is a very complex interplay of various neurotransmitters, which says this really is an important part of our existence. Evolution wouldn’t have come up with something useless,” Sadigh said. “When those ratios are disturbed, either through too much or too little sleep and dreaming, you have to ask the question, which comes first? Is it the psychological state affecting the neurological state or is it the neurological affecting the psychological?”

Dreams can confound even those who study them. Sadigh has the high school dream, which he finds puzzling mid-dream. “Part of me kicks in and says, ‘I have a PhD. I shouldn’t be in a high school social studies class.’ But dreams reveal emotional stress and concerns. It’s important to look at them to figure out what’s going on in your files.”

He added: “We are fascinating creatures. It’s important to know the neurological things but it’s also important to figure out life itself. Dreams and the creativity that comes from them can be a source of delight or torment.”