A small amount of electrical current could be the key to letting people control their dreams. A new study led from the Goethe University Frankfurt has found that by applying current in certain frequencies to a sleeper's scalp, just above the forehead, that person may be able to gain some control over their dreams. In particular, that control included allowing people, to some degree, to recognize that they were dreaming and to view the dream as if from a third-person perspective — traits that the researchers say qualify these as lucid dreams.

As it turned out, that electrical signal seems to be a cause of lucid dreams, potentially because it stimulates areas of the brain relating to higher-order consciousness. Only certain frequencies were able to properly stimulate the area though, particularly 40Hz, which resulted in over three-quarters of dreams being classified as lucid, and to a lesser extent 25Hz, which led to over half of dreams being qualified as lucid. In the tests, the current was only applied for a matter of seconds, a few minutes after a test subject entered the REM stage of sleep.

The type of lucidity that appeared is basic for now, however, and doesn't necessarily involve the type of robust control over one's dreams that lucid dreaming is said to provide. One account from the study of a lucid dream at 40Hz illustrates their limitations:

I was dreaming about lemon cake. It looked translucent, but then again, it didn’t. It was a bit like in an animated movie, like The Simpsons. And then I started falling and the scenery changed and I was talking to Matthias Schweighöfer [a German actor] and two foreign exchange students. And I was wondering about the actor and they told me “yes, you met him before,” so then I realized “oops, you are dreaming.” I mean, while I was dreaming! So strange!

The study was also conducted on a small group of subjects, just 27, so the results are limited. Still, the researchers say that their results signal that stimulation at 40Hz is relevant to triggering consciousness in dreams — and potentially even while awake too. The researchers believe that this could eventually even be used as a clinical treatment, perhaps even helping treat schizophrenia by restoring dysfunctional pathways or treat post-traumatic stress disorder for those with nightmares by allowing them to change the content of their dreams.