I just got back from a weekend trip to Hawaii, but before I left, I read an interesting study on donepizil. Donepizil is a substance that has been shown to help with Alzheimer's disease. It does this by increasing levels of a neurotransmitter in the brain called acetylcholine. As it turns out, acetylcholine is at high levels in the brain during dreaming sleep. Stephen LaBerge theorized that increasing these levels would induce lucid dreaming and it appears he was correct. In a 2004 randomized, double-blind, placebo controlled study involving 10 subjects, he found that the odds of having a lucid dream on donepizil 10 mg is 24.3 times higher than the odds of having a lucid dream on placebo. He also notes that they have tested rivastigmine (6-12 mg) and galantamine (8-16 mg) with the same results but "perhaps fewer side effects." It is unclear whether any other induction technique was used (in combination with the medications). This is very intriguing data and opens up a new avenue for lucid dream induction: substance induced lucid dreams. However, it also begs the ethical question of whether using a substance to induce lucid dreams is the right thing to do.
Stephen LaBerge and Howard Rheingold introduced the concept of Dreamsigns in the 1990 book "Exploring the World of Lucid Dreaming." In short, a Dreamsign (all one word) is "a peculiar event or object in a dream that can be used as an indicator that you are dreaming." The idea is that if you can familiarize yourself with your personal Dreamsigns, you will more likely recognize them in your dreams and become lucid. In the book, they propose a somewhat complicated system for categorizing and inventorying your own personal Dreamsigns. I have always found this concept intriguing, but too laborious to be practical. However, recently I was reviewing the research that went into creating their categorization system (in Lynne Levitan's 1992 article "A thousand and one nights of exploring lucid dreaming") and noticed an interesting bit of information. The two most common Dreamsigns (and with high likelihood of triggering lucidity) were: 1) "Dreamer does something unlikely or impossible in waking life" and 2) "Dreamer experiences unusually intense emotions." Thus, I would propose that a simplified version of Dreamsign familiarity/recognition would be to focus on just these two categories. So, focusing on Dreamsigns like flying or intense surprise/happiness/fear might give you more "bang for your buck" and may not require such intensive analysis of your dream diaries.
The late German researcher Paul Tholey published an amazing paper in 1983 in the journal "Perceptual and Motor Skills" entitled "Techniques for inducing and manipulating lucid dreams." I have gone back to this article over and over again, and today I noted a technique that I had glossed over previously. He did not give it a title, so I am calling it the "Dream Figure Contract Technique." Tholey describes a technique he himself had used based on the phenomenon that dream figures will often comment on the state of consciousness of the dreamer. His idea was "willfully allowing a certain dream figure to aid him in attaining lucidity." He reported making an agreement with a dream figure (while in a lucid dream) to meet him in his next dream and "tell him that he was dreaming." It worked! No further research is cited, nor how often this worked for him.