Over the last two years, I've spent most of my waking life thinking about sleep.
It began with a painful accident. I woke up in the middle of the night to find myself on my back in a hallway with a searing pain in my knee. I quickly pieced together that I had sleepwalked into a wall. An admission by my doctor a few days later that he didn't know much about sleep and couldn't help led me to set out to discover why a third of my life was passing by, unexamined and unaccounted for, all while shrouded in mystery.
I talked with everyone from doctors to military generals to constitutional scholars to find out how sleep was affecting our lives. Yet whenever I talked with someone outside of that relatively small circle of professionals, they always had one question: what was up with their dreams?
Like everything else with sleep, it's a deceptively complex issue. Whether dreams have any inherent meaning or function is a question that's been with us since early humans scratched out the first written language. Ancient Greeks thought they were omens. Early Muslims believed dream interpretation was a practice sanctioned by the Koran. And the Bible is a veritable dream fest.
But science has long been skeptical. Until Freud published The Interpretation of Dreams most researchers believed that dreams were essentially noise. Freud's theory that dreams were laden with symbols that reflected our unconscious thoughts flourished for a few decades until better technology - combined with the discovery that most dreams occur during rapid eye movement sleep - led many researchers to give up trying to make sense of the strange stories our brains come up with each night while we're sleeping.
Yet that conception may be changing. A number of recent studies suggest that dreaming may in fact be the time that your brain consolidates what it learns each day and prepares for the challenges it will face the next. While there may not be any logical plot or adherence to the rhythms of your daily life, your dreams could be nothing more than the brain's chance for a dress rehearsal.
For evidence, researchers had to look no farther than video games. Robert Stickgold, a professor of psychiatry at Harvard Medical School, conducted a study in which college students were asked to play the game Tetris before falling asleep. Then, he woke them up later in the night and asked what they were dreaming about.
The idea behind the study came to Stickgold after he had spent half of a day mountain climbing in Vermont. As he drifted off to sleep, he kept waking up with the strange sensation that his hands were still on the stocks. Tetris, he reasoned, may be a way to test if the mind continues to rehash its recent experiences.
When subjects in his study were woken up and asked what they were dreaming about, they often offered the same basic tale: watching shapes falling down, just like in the video game. Intriguingly, these dreams were even recorded by a number of amnesiacs who had little active memory of actually playing the game. The number of Tetris dreams increased the second night of the study. It was as if the brain realized that sorting shapes was becoming an ongoing requirement, and it devoted extra time for practice.
It looks like it wasn't just a function of the brain transitioning between waking life and dreamland. Some studies have shown that as subjects are allowed to sleep longer, their dreams tend to combine elements of what they experienced each day with the information they already knew. Others have shown that subjects who get to the dreaming stage of sleep are able to solve puzzles faster, make better connections between abstract ideas, and perform novel tasks like typing numbers with their non-dominant hands better than those who don't get as much time in that crucial stage of sleep.
Dreaming, in this view, could be when the brain finds connections between all of the things stored in its mental filing cabinets. But that's not all. Dreams could also help us sort through the everyday anxieties that our minds grapple with.
It's a position by a trove of 50,000 dream journals collected by a Calvin Hall, a late professor at Case Western University, and William Domhoff, a professor at the University of California, Santa Cruz. After running an analysis that looked at the content of each dream, Domhoff now sees these storylines that take place in this stage of sleep as simply a reflection of our waking lives, with no need for any sort of Freudian analysis. Looking at history of one person's dreams tends to show that our brains have more upsetting dreams the night before we face a challenging task, whether that means starting school the next day or giving a presentation to our new boss.
Researchers now believe that dreaming about the same thing each night could be a sign that the brain hasn't been able to accept a particularly traumatic experience. As such, focusing on techniques to lessen the frequency of nightmares is becoming a larger part of treatments for conditions like post-traumatic stress disorder.
That, in fact, looks like future of dream studies: finding the practical amid the surreal.
David K Randall is a senior reporter at Reuters and the author of Dreamland: Adventures in the Strange Science of Sleep [W.W. Norton, $25.95].