Reality checks are a popular way to trigger lucid dreams. They may not be 100% reliable, but they are very easy and habit forming.
If you are practicing other lucidity techniques, perform daily reality checks as well for good measure. They will help with "lucid living" (building greater self-awareness while awake) which leads to more vivid and lucid dreams.
To learn lucid dreaming, you must be able to spot the difference between a dream and waking reality.
"Once upon a time, I dreamt I was a butterfly, flittering hither and thither, to all intents and purposes a butterfly ...suddenly I awoke... Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly dreaming I am a man."
Normally when you dream, you accept it as real life. It's only when you wake up that you realize something was strange.
By integrating reality checks into your waking life, you will soon do them in your dreams. This will snap your conscious mind to realizing: 'Hey - I'm dreaming!"
So, what makes a really good reality check that works in the surreal, illogical nature of the dream world? Let's think this through for a moment.
How do you know that you are awake right now? You might say:
Unfortunately, this all applies to the dream world too. That's why seeing, feeling, awareness and knowledge of your existence do not help you become lucid. (Remember that your dreaming mind lacks clarity of thought and can't draw the same logical conclusions as your waking mind.)
In order to recognize when you're dreaming, you need to spark that "Eureka!" moment with a definitive test: a simple question combined with a pre-determined action that you already know is impossible in the waking world.
My default reality check is pushing two fingers from my right hand into the palm of my left hand and willing them to pass straight through. In waking life, this is discreet and always yields the same resistance. In a dream, my willing the fingers to pass through causes it to happen 90% of the time.
And then I know... I'm dreaming!
(At this realization your conscious brain will ignite in the dream, your environment will surge into focus and you will have a real sense of who you are, where you are, and what you want to do next. For more information on the transition to lucidity, see What Do Lucid Dreams Feel Like?)
Of course, the action is not enough. You need to ask the question "Am I dreaming?" and truly mean it. You need to look around your environment every time you do a reality check, and consider "Is this real?"
I like to question the solidity of my surroundings. For instance, I might look at a cup on my desk and wonder does that really exist or am I imagining it? Does it go away when I stop looking at it? How about the air - can I see the air? Is it warm, cold, dense, sparse, colorful, invisible? This is how you build self-awareness: questioning your own feelings and perceptions in the moment.
At the same time, you'll perform your reality check of pushing your fingers into your palm. Do this a dozen times a day (leave notes to remind yourself) and allow each check to take anything from a few seconds to few minutes. Be sure to come to a well-informed decision each time. Don't just ask the question and forget about it. Truly mean what you say, and reach a conclusion.
Soon you will habitually ask this question in a dream. Bingo. Your mind will be jogged into critical thinking mode and you'll conclude that you're dreaming.
Use the finger check if you like, or try out these other effective tests:
For good measure, perform two reality checks each time. If the first one doesn't work (it happens) you have a failsafe. I combine fingers with the palm check.
Sometimes I try to push my hand through the desk or wall. It is a wonderful feeling when you actually can push your hand through a solid object in a lucid dream. Your lucidity makes this feel real - and, naturally, very weird!
The human brain creates neural constructs based experiential learning: patterns of thinking based on our real life experiences. For instance, since you have had the experience of gravity your whole life, you don't need to repeatedly question it. You simply know that you can't will yourself to float or take off.
And so most adults mosey on through life without ever questioning the world around us. We know that the sky is blue, that we can't control objects with our minds, and that walls are too solid to walk through. We become so accustomed to our reality we forget to question it. And this applies in the dream world too.
However, if you do decide to question your reality on a regular basis, it increases your level of self-awareness in the real world. It pulls your consciousness into the moment. And when this becomes second nature in waking life, it will become second nature in dreams too.
And this is a direct line to tapping lucid dreams.
Attaining a good level of self-awareness will not come overnight. But it's a fast learning curve. A beginner's progress could well be exponential.
So, pay attention to your surroundings. Study them in detail. And most importantly, question their nature. Do your hands belong to you? How would it look if you had 12 fingers? Can imagine them melting into the furniture?
Have fun with visualizations and tricks of the mind. You're aiming to short circuit your brain and edit programming that has been in place for decades...
For more tips see my article How to Improve Your Self Awareness.
As this is a very popular lucid dreaming technique, I get a lot of questions about how to do reality checks (and why they don't always work). I've summarized the most common questions and answers below:
Set up triggers that remind you to perform a reality check, such as: a note on your computer screen, telephone, bathroom tap, schoolbooks, or even write an L for lucid on the back of your hand.
You can also mentally set up trigger points that relate to your day. Do a reality check every time you: walk up or down stairs, hear your digital watch beep, receive a text message, unlock a door, hang up the phone, and so on.
First, ensure you're doing your checks mindfully and coming to a reason-based conclusion every time. Every check should hold real personal perspective.
Second, make sure you're keeping a dream journal and recording at least one dream per night. You may well have performed a reality check in a dream (and even become lucid) but just didn't remember it!
Fourth, be patient. You are entraining a new habit into your daily life and it may take days or weeks for it to filter through to your dream life. Rest assured, like most of our daily habits, you will dream about it eventually.
The most likely explanation is that you're not performing your waking reality checks with enough mindfulness. When you attempt the impossible action, make sure you're really trying to do it and not just kidding yourself. And when you ask the question - "Am I dreaming?" - be sure to truly ponder that concept. Imagine what a dream feels like, what you would do if you were dreaming right now, and then snap yourself back into reality to compare the feeling.
Occasionally a reality check fails through no fault of your own. You may simply be having a vivid dream that is all too normal to accept as a dream. It's a weird mind space, and particularly common in false awakenings (which is why you should always do a reality check every time you wake up).
The best solution is to perform a second reality check as a fail-safe. If you still can't validate your dreamstate, but have some basic level of dream control, then simply explore the dream until it gives itself away. Something irregular will eventually pop up if you keep pulling at the thread. Full lucidity will ensue.