The ability to become conscious in a dream, called lucid dreaming, is a phenomenon that has been recognized by different cultures throughout recorded history. However, if you are just becoming familiar with the field of lucid dreaming, the first thing you might ask is, “what is a lucid dream?”
People all over the world have induced dreams in which they maintained conscious awareness for the purposes of spiritual seeking, philosophical exploration, self-improvement and even recreation. Tibetan monks believe that increased lucidity in dreams and dream control is an important step on the path to enlightenment, and have practiced meditation-based lucid dreaming techniques for centuries. More recently, French existentialist philosopher René Descartes’ lucid dreams led him to question whether there was anything that made waking reality more “real”, and inspired him to coin the famous maxim, “I think, therefore I am”. However, until the early twentieth century, no serious scientific research had been done to address the question, “what is a lucid dream?”
In 1913, Dutch psychologist and writer Frederik van Eeden coined the term “lucid dream”; according to his definition, a lucid dream is a dream in which a person is aware that he or she is dreaming. A lot of people new to lucid dreaming often assume that you must have control in a dream for it to be lucid. Not true! Many accomplished lucid dreamers might just let a dream narrative progress and watch it unfold as a fully conscious, lucid observer. Your level of awareness that you are dreaming is what makes a dream lucid or not. It’s also possible for you to achieve low-level lucidity in a dream, where you realize or wonder if it’s a dream only for a brief moment. Since achieving awareness, not control, in a dream is the definition of a lucid dream, most guides to lucid dreaming focus on techniques such as reality checks which you can use to jog your awareness in to recognizing that you are dreaming.
The requirement that you must be aware in your dream for it to be lucid separates lucid dreams from other related altered states of consciousness, such as out-of-body experiences, near-death experiences, and even alien/UFO abduction experiences. Many of these states incorporate phenomena similar to what you might encounter at the onset of a lucid dream: tingling vibrations, a feeling of paralysis often accompanied by intense emotions, or a feeling of leaving your physical body. The difference is that people who have had out-of-body, near-death, or alien abduction experiences often truly believe at the time that what happening to them is real. Although it might incorporate similar phenomena, in a lucid dream the dreamer becomes aware at some point during the experience that the world around them is a construct of the mind.
What is a lucid dream, physiologically speaking? In the first experiments with lucid dreaming, neuroscientists such as Stephen LaBerge were trying to prove that lucid dreaming was a real phenomenon. The second question that these researchers tackled, logically enough, was regarding what parts of the brain become active when someone is experiencing a lucid dream. Neuroscientist Allan J. Hobson has speculated that during REM sleep an activation of the part of the prefrontal cortex that controls working memory might allow the dreamer to become lucid in a dream. This area of the brain controls our access to memory and self-awareness, and is normally dormant during REM sleep. The subconscious act of dreaming is regulated by deep brain structures which remain active and creative even after a person becomes lucid in the dream. This means that, far from having to consciously maintain your dream once you become lucid, you can just as easily sit back and watch it play out as a lucid observer. (However, you can also use certain techniques to prolong your lucid dream, if you wish)
The feeling of waking up from a lucid dream may give us the most interesting insight into what a lucid dream is: in contrast to an ordinary dream or a false awakening, when people wake up from a lucid dream it still feels real and continuous with the waking state. In her 1991 article on the subject, Susan Blackmore suggests that this seamless transition might be possible because our model of ourselves is closer in a lucid dream to the model of ourselves we maintain in waking life. When one is awake, sensory input helps the brain create a consistent model of reality with the individual as the embodied point of view at the center. In dreams this sensory input is removed, leaving the brain free to create different, competing models of reality. Whichever model of reality, or dream, is most stable at any given moment feels real. Recall your dreams in enough detail and you might realize that there is no distinct “you” witnessing and participating in the events in your (subconscious) dreams: there are thoughts, feelings and actions that different dream versions of you perform, but because the parts of your brain responsible for self-awareness and memory are dormant in a normal dream, there is no consistent model of you.
Lucid dreaming changes all that. The higher level of prefrontal cortex activity in a lucid dream may be just enough for your brain to create a model of you within your dream that is much closer to the model of you that your thoughts and senses combine to create when awake. Blackmore suggests that your lucid dreaming self is congruous enough with your waking self to enable you to notice inconsistencies in your dream model of reality. You would then usually become aware that you are dreaming. Since your dream identity is closer to your waking identity in a lucid dream than a normal dream, you are able to remember lucid dreams much better upon waking.