Out of all of the substances used for practicing lucid dreaming, only coffee is readily obtainable. However, it should only be taken by novices who sleep too hard. For everyone else, there’s no sense in using it, as one’s practice should be natural.
The essence of the this tactic is to use the deferred method in conjunction with taking coffee. For example: a practitioner sleeps for 6 hours, gets up, drinks coffee, and goes back to sleep with the intention of catching the next awakening in order to use indirect techniques or in expectation of becoming consciousness while dreaming. Thanks to coffee’s invigorating properties, one will be at a higher state of awareness during subsequent awakenings, and awakenings themselves will be more frequent. There will also be a high likelihood of becoming consciousness while dreaming.
While some hold it’s best to take a double dose of the drink, such things are purely individual, and everyone has to find what works for them. Some enjoy the same level of success when drinking black tea instead of coffee.