The phenomenon of lucid dreaming occurs when dreamers become aware that they are in the midst of a dream. The most unusual aspect of this state is that lucid dreamers can consciously alter the content of their dreams. Stephen LaBerge, a Stanford-trained psychologist, was the first person to scientifically demonstrate the existence of lucid dreams.

Because the dream landscape is a product of the dreamer’s mind, it should be possible to simply “will” the dream to change, just as one does in certain visualization exercises. Some therapists have already begun to make therapeutic use of this technique, asking people who are nightmare-prone, for instance, to attempt to manipulate their dreams so that they will have happy endings.

LaBerge recognized the potential usefulness of the lucid dream state early in his research and developed a product that he called DreamLight for helping dreamers to initiate lucid dreaming. Robert Van de Castle, in his important work Our Dreaming Mind (pp. 447–48—see Sources), describes DreamLight as follows:

It consists of a Lone Ranger-style mask that picks up eye movements with an infrared detection device. When a miniature computer counts eye movements to determine that a rapid eye movement (REM) period is probably occurring, flashing red lights are turned on within the mask. Awareness of the flashing red lights then acts as a signal to the dreamer that a REM period is occurring, and the dreamer can use that information to achieve lucidity.