Can Electrical Brain Stimulation Induce Lucid Dreams?

Lucid dreaming is a phenomenon where you become aware of the fact that you are dreaming while still within the dream. Several sleep laboratories around the world are interested in studying lucid dreams, but unfortunately, it is quite difficult to capture lucid dreams while a subject sleeps in the laboratory. This is because lucid dreams do not occur very often. For instance, although over half the population has experienced at least one lucid dream in their lifetime, only about 25% of individuals have lucid dreams on a monthly basis.

Because of this, the majority of research to date has focused on improving methods to induce lucid dreams more reliably. One study published in 2014 found that applying electrical stimulation to the brain could increase lucidity. Naturally during sleep, our brain cycles through different rhythms of electrical activity. In lucid dreams, we think that these rhythms become faster, more like wakeful brain activity. So, researchers decided to apply fast electrical currents to the scalp, to modulate underlying brain activity toward a desired frequency.

Specifically, experimenters applied "transcranial Alternating Current" or "tAC" stimulation at 40 Hz (40 cycles per second) to the frontal region of the scalp, and found that it increased self-awareness in dreams. However, there have been no attempts to replicate this study, until now.

Researchers at the Dream and Nightmare Laboratory in Montreal recently conducted a similar study to test whether applying 40 Hz tAC stimulation to the frontal brain region during REM sleep increases the occurrence of lucid dreams. The findings were recently published in a Special Issue on Dream Engineering in the journal Consciousness and Cognition.

In the study, participants were invited to the sleep laboratory for two morning naps. During one of the naps, after the participant entered REM sleep for 2 minutes, the experimenters applied 40 Hz tAC stimulation for 2 and a half minutes, at intervals of 30 seconds on and 30 seconds off. During the other nap, the experimenter did not apply stimulation. Participants were then awakened for dream reports after about 10 minutes of REM sleep (and at least 3 minutes after stimulation ended).

One important component of the study is that participants were asked to signal if they became lucid in a dream, by looking quickly to the left and right with eye movements while still in their dream. This is a standard method in sleep laboratory studies of lucid dreaming. All of the participants have electrodes placed on either side of their eyes, so the left-right sequence of eye movements is clearly visible on recordings of activity from these eye electrodes. Thus, the eye signal provides objective evidence that a participant is lucid while asleep.

In total 40 participants were recruited for this study. After excluding participants who missed sessions, had inadequate REM sleep or no dream recall, the results of the study were based on recordings of 27 naps with tAC stimulation, and 23 naps without stimulation.

In 5 of the 27 naps with stimulation, participants became lucid and successfully signaled with Left-Right eye movements. Below is one example of a lucid dream report:

When I moved my eyes the way I was shown before my dream I had just realized I was asleep and that I was aware that I was dreaming. So what I was dreaming at this moment was not for me a dream but more like reality. I was at the laboratory in bed with the electrodes and everything. This moment was very short. It was like I told myself: ''The experiment is done, I moved my eyes and it worked, I can let myself go now and dream without thinking if I am lucid or not."

Furthermore, in 4 of the 23 naps without stimulation, participants became lucid and signaled with eye movements. Below is one example:

At the beginning, I was in my house and I went to see my rabbits. I realised that one of them was gray and not black and I thought that it was not normal. It was at that moment that I realised that I was in a dream. Then I remembered everything. All the instructions on what I was supposed to do if I had a lucid dream, so I looked from left to right five times.

Thus, the main result of the study is that lucid dreams were observed in 18.5% of the naps with stimulation, and 17.4% of the naps without stimulation. There was no significant difference in lucid dreaming success between these two conditions.

These results do not support the initial study findings and cast doubt on claims that 40 Hz tAC stimulation increases lucid dreaming. This underscores the importance of replication studies in research, especially given that several consumer devices have been developed since 2014 that advertise their ability to induce lucid dreams using tAC stimulation. Such devices are untested and scientifically premature.

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While the results do not support the use of tAC stimulation to induce lucid dreams, the overall lucid dreaming success in the study is quite encouraging. The researchers observed lucid dreams in 18% (9 out of 50) of the brief 90-minute morning naps in the sleep laboratory. In general, it seems that morning REM sleep is ideal for lucid dreaming, since the likelihood of lucid dreaming increases across a night of sleep and peaks in the morning (LaBerge, Levitan, & Dement, 1986).

Perhaps a simple morning nap, without the brain zap, is a more sensible approach to lucid dreaming.