In the article, “Psychophysiological Correlates of Lucid Dreaming”, Holzinger, LaBerge, and Levitan (2006) did a study on studying the electrophysiological differences between lucid and nonlucid dreaming in REM sleep. The study involved the experiences of seven men and four women during lucid sleep for two nights in a laboratory (Holzinger et al., 2006). They took polysomnographic recordings while these men and women slept, using EEG signals to produce five different frequency bands (Holzinger et al., 2006). They used reports from subjective dreaming and signals made by eye movements made by the subjects in response to light stimuli, which indicated a REM state to determined lucidity (Holzinger et al., 2006).
The state when one is dreaming and is aware that they are dreaming and having the ability to control what happens in their dreams is known as lucid dreaming (Holzinger, LaBerge, and Levitan, 2006). While in this state of dreaming, all subjects were able to remember things from their waking lives, act willingly within their dreams, and the ability to reason clearly (Holzinger et al., 2006). There are seven different characteristics of lucid dreaming, which include, full awareness of the dream state, awareness of the possibility of making free decisions, clear consciousness of the dreamer, perception by all senses, a full memory of the waking life, full memory of all lucid dreaming experiences in both the waking state and in the dreaming state, and awareness of the meaning of symbols (Holzinger et al., 2006).
Lucid dreaming has been suggested to begin in the REM sleep after the first physiological recordings were taken (Holzinger, LaBerge, and Levitan, 2006).
During this study, REM sleep was the only way lucid dreaming was observed (Holzinger et al., 2006). Lucid dreaming is something that can be learned and is hard to initiate, in order to help the subjects know that they were dreaming while they were in the REM state had tape recordings of the phrase, “This is a dream,” played while in this state (Holzinger et al., 2006). The subjects also had their eye movements, heart rate, blood pressure, and skin potential compared from both lucid and nonlucid dreaming, which the researchers discovered that lucid dreaming occurred during the REM periods that are characterized by the increase of physiological activations (Holzinger et al., 2006).
All subjects were equipped with sleep masks that contained two bright lights that would flash continuously throughout their sleeping cycle at a set time differentiation (Holzinger, LaBerge, and Levitan, 2006).
Each subject was asked to make certain eye movements while they were in the lucid state (Holzinger et al., 2006).
If they did not make the requested eye movements after two sets of light flashes and eventually awakened if they still didn’t respond (Holzinger et al., 2006). If one of the subjects gave the eye movement signal that they were in a waking state but were still in the REM state was referred to as “false awakening,” (Holzinger et al., 2006). There were two requirements needed for a dream to be considered a lucid dream, one was that a designated eye signal, called LR2, visible in polysomnography and the second was a report given by the subject claiming to have been in the lucid state (Holzinger et al., 2006). Both of these requirements were then tested by two individual researchers to make sure that the subject was actually in a lucid state (Holzinger et al., 2006).
The differences of lucid and nonlucid dreaming are determined by the fact that while in the lucid state the subject had more beta-1 activity, where the differences reached statistical significance in the subject’s parietal lobes (Holzinger, LaBerge, and Levitan, 2006). There were also hemispherical differences between both dream states (Holzinger et al., 2006). The left parietal lobe had the highest increase, while the differences did not actually reach statistical significance (Holzinger et al., 2006). The researchers concluded that their results meant that lucid dreaming, while conscious, is based on the understanding of the phrase “This is a dream,” (Holzinger et al., 2006).
Holzinger, B., LaBerge, S., & Levitan, L. (2006). Psychophysiological Correlates of Lucid Dreaming. Dreaming, 16(2), 88-95. Retrieved October 10th, 2006 from EBSCO Host database.
