Inception is an absurdly complicated, clattering contraption of a movie that impresses only in a mechanical, Rube Goldberg–ish way. My intellect had to work so hard to figure out what was happening that my emotions never got engaged. But the flick gives me an excuse to revisit a topic that's fascinated me ever since I had an odd dream more than 40 years ago: I was sitting on a stoop with two pals when suddenly I realized we were in a dream—my dream. When I told my buddies, they mocked me. "Yeah, right! We're not real! We're just in your dream!" I woke up muttering, "I told you." Story of my life.

The Dutch psychiatrist Frederik Willem van Eeden coined the term "lucid dreaming" in 1913, but descriptions of dreams in which you know you're dreaming date back at least to Aristotle. Most people can recall at least one lucid dream, and perhaps one in 10 has them regularly. A half century ago some researchers still insisted that lucid dreaming is a contradiction in terms; if we are aware we are dreaming, we must be at least semiawake.

In the 1970s, however, the psychophysiologist Stephen LaBerge demonstrated the reality of lucid dreams in experiments at Stanford University. (See the discussion of his work in another Inception-inspired article on this site, "How Can You Control Your Dreams?".) LaBerge employed lucid-dreaming adepts that he dubbed "oneironauts," from the Greek words for "dream" and "explorer". Oneironauts learned to signal that they were lucid with prearranged eye movements while an EEG (electroencephalogram) confirmed that they were in the REM (rapid eye movement) stage of sleep, when dreams usually occur. (Eye muscles can be controlled during REM sleep, whereas most other muscles are immobilized.)

LaBerge showed that activities such as counting numbers or having sex evoke similar neural and physiological responses in both the dreaming and waking states—and if your dream self holds its breath, your real self does, too. Moreover, events take about the same time to unfold in lucid dreams as they would in real life. (Inception posits, and some researchers still believe, that dream time is often compressed so that a dream that seems subjectively to take an hour only takes a few seconds.)

LaBerge, whom I interviewed in 1994 for the now-defunct science magazine Omni, has morphed into a somewhat New-Agey promoter. He touts lucid dreams as an all-purpose self-improvement tool that can help us overcome fears, tap into our creative powers, practice a sales pitch or achieve spiritual enlightenment. LaBerge has written a half dozen books on lucid dreaming, and in 1986 he created the Lucidity Institute, which disseminates information and sponsors research and workshops. A workshop in Hawaii this fall will "present instructions on methods of developing the mental skills that foster lucidity and on directing consciousness within both dreaming and waking states towards fulfillment of personal goals."

To his credit, LaBerge offers tips for cultivating lucidity without flying to exotic locales. You will lucid dream more often if you think about dreaming while you're awake. You should also keep asking yourself, "Is this a dream?" And keep an eye out for weirdness: if you are flying or chatting up Lady Gaga, you probably are dreaming. Also, look for text of any kind, because in dreams written words usually look different every time you try to read them.

A technique that LaBerge calls mnemonic induction of lucid dreams, or MILD, involves waking up an hour earlier than usual in the morning, recalling your last dream, and going asleep again while thinking, "The next time I'm dreaming, I want to remember I'm dreaming." Lucid dreams occur most often in the morning just before awakening.

LaBerge has experimented with artificial means for promoting lucidity, including the essential nutrient choline and other substances that supposedly intensify dreams; tapes that whisper, "This is a dream"; vibrators that gently jiggle the bed; and an electronic mask called the NovaDreamer. When an infrared sensor in the mask detects REM-type eye-twitches, the mask emits lights or sounds that, ideally, make the sleeper lucid without completely waking her up.

While doing my article on LaBerge in 1994, I tried his MILD technique and had a few lucid dreams, which were very cool. I haven't had one, or tried to have one, in many years. Too lazy, I suppose. But a couple of things that LaBerge told me have stuck with me.

One is that we are, in a way, always dreaming. That is, our neocortex constantly generates scenes and stories based on neural data available to it. While we are awake, neural data come from sensory perceptions of external phenomena; while we sleep, the data are unconstrained—or only slightly constrained—by external input.

I'm even more haunted by LaBerge's description of an ancient Tibetan Buddhist practice called dream yoga, which involves becoming lucid in and then mastering the content of dreams. Dream yoga can be lots of fun; you can do and be anything—anything!—in your dreams. But its ultimate goal is to realize that reality is a dream, too. Enlightenment, the supreme goal of Buddhists, is a kind of meta-lucidity, in which you wake up from reality.

This idea once appealed to me, but now it strikes me as the most perverse form of escapism. Maybe that's why I didn't like Inception, because it suggests that we're never really awake; we just shuttle from one dream to another. If life is but a dream, I don't want to wake up.

Painting by Albert Joseph Moore, courtesy Wikimedia Commons