Mahayana doctrine about dreams and illusions

When we are children we often have a hard time getting over nightmares and vivid dreams. Similarly, we often have a hard time with movies / video games. We mistake illusion for reality and vice versa. We are ignorant of how things work, but as we grow up we learn more and more about how things work. Our parents can teach us that dreams/nightmares aren’t real and therefore are not worth getting as bothered about.

As a consequence, generally speaking adults are better at distinguishing between real things and unreal things. Movies and nightmares sometimes still bother us, but not as much as when we were kids. Check yourself, isn’t this true?

To the extent that unreal things - that we know are unreal - still bother us it is generally because we buy into them, right? Don’t we call this “suspending disbelief?” If you are watching a movie and are emotionally invested and then notice a glitch or continuity break in the movie doesn’t this “take you out of the movie” and disrupt the emotional connection?

If you meet someone with a lot of makeup on and think them very attractive and then one day see them without the makeup doesn’t this, “break the spell?”

If you are in the desert and very thirsty and see a mirage aren’t you disappointed to find it, “isn’t real?”

Your childhood dreams occurred when you had a harder time distinguishing real from unreal, right? Your adult dream where you emotionally invested in the deceased person was craving for that person to be real or suspending disbelief that they were not, right? Were you mindful at every second that they were not? Any joy you felt was predicated on whatever success you had in seeing them as real, right? Any disappointment you felt was predicated on whatever failure you had in seeing them as real, right?

Your exam dream is a good example! That anxiety you had that you’d failed turned to relief when you woke up. If you were mindful every second while dreaming that you were dreaming would the same anxiety have arisen in the first place?

The teaching regarding everything as like illusion is not exclusive to Mahayana IMO and it most definitely does not mean that nothing exists or that nothing matters. That is nihilism and thinking that is indicative of incorrect understanding. One should back away from that belief with all due haste and understand that one has gone astray lest one destroy oneself and the aims of all those who are counting on one to become Buddha.

I apologize for whatever mistakes I have made in explanation that might cause the arising of nihilism in another and I implore to please please know that is not what I intend. It is the result of my own unskillful communication.

Is there some standard Mahayana doctrine about dreams and illusions?

Not sure if there is anything like "official Mahayana doctrine" about dreams, but the examples of dreaming are used in the verbal tradition all the time. For example, from this lecture by Thrangu Rinpoche:

[Speaking about the first link of Twelve Nidanas.] This basic ignorance concerns two things: external phenomena and mind. First we believe the appearances such as trees and rocks that we see in our mind are external and real objects. That is the nature of mistaken appearance. Second, we believe that internal mind is truly existent.

For example, when we sleep dreams are an appearance that arise out of the luminosity of the mind. The luminosity of mind does not stop just because we go to sleep; the mind's luminosity when we dream appears in our mind which "sees" those various appearances as external objects. We know, however, that those mountains and elephants that appear in our dreams were created by the luminosity of the mind and do not exist. Since we know that they do not exist, we can also understand that the "I" or the mind seeing all these appearances in the dream does not exist either.

Now when we apply this example of our experience of dreaming to our experience while awake, we can see that there are external appearances and internal appearances (thoughts and feelings) and that these also do not exist.

...

[Speaking about the second link, Sankharas, which he calls "latencies".] Let us take an example of an elephant — one that we see while we are asleep and dreaming and one that we see while we are awake. In both cases an elephant appears to us as a real elephant. While we are awake, the outside sensory impression of an elephant appears real, because our impression of an elephant matches these internal latencies which come from the eighth consciousness. In a dream the latencies of the elephant also come from the eighth consciousness and appear to us, and we see it at the time as real. So we see that the dream elephant and the real elephant are the same in two respects: they really do appear due to latencies, and they are both truly empty.

Paraphrasing, according to this presentation, so-called external objects as well as internal mind (=thoughts & feelings) arise out of the luminosity of the mind. External objects arise when outside sensory impressions match internal latencies, while internal objects arise out of the same internal latencies without any sensory impressions. This is usually summarized as "appearances are mind". At the same time, to say that "mind is a real entity" or that "mind is truly existent" is a mistake. The true nature of mind is emptiness which has the "quality of luminous clarity", "quality of knowing" and "spontaneous presence". So all our experiences, both when dreaming and when awake, are projections of mind's "latencies"; these "latencies" or "tendencies" are imprints from the previous experiences -- and this is how the cycle of ignorance feeds itself.

I guess the point of comparison between dreaming and wakeful states, at least as used in this presentation, is that both types of experiences are projections of imprints from the previous experiences and in this sense are equally unreal.

How is the doctrine meant to be used?

I think the practical side here, is that: once we know that the desirable or the frightening object (or situation) is a projection of our mind, we stop reifying it as something separate from the mind and so it loses it's power and grasp.

For example, I recently saw a dream in which I was physically attacked by someone stronger than myself. While I (kinda) knew it was a dream, I did not realize the enemy was actually my own projection. Then, as I knew I could not win that fight, I paused and contemplated an idea that both the villain in that dream as well as my sense of "I, the victim" were actually two parts of the same mind which was, therefore, fighting with itself! At this point my feeling of fear towards the attacker was gone and at the same time the attacker himself seemingly lost his hostility towards me. I was able to touch his forehead with mine and he was sucked into my head as a drop of melted metal from Terminator 2.

Several months after that dream, I had a conversation with someone intellectually smarter and emotionally tougher than me, whose judgement I was always afraid of. Habitually, I reflected on something I just said and thought that I must be looking very stupid from his perspective. Then suddenly, I remembered my dream and realized that my idea of his judgement was actually my own projection, since the guy actually never ever said anything or otherwise non-verbally indicated any negative opinion about my intellectual or emotional inferiority. As soon as I realized that this was my own projection, I was able to integrate the two parts of my mind (the judging one and the one being judged).

So I think the point of all this talk about dreams and projections, is that reification of our projections as something objective leads to suffering, and cessation of reification leads to cessation of suffering.

That said, as is shown in my dream example, knowing that objects are unreal is not enough. I too in my dream knew that it was a dream - and yet I kept fighting my attacker out of habit and disgust, following my emotional habits (latencies/imprints). It's only when I made a conscious effort to re-interpret the situation in different terms, to see it from a different perspective - is when the freedom from projections was attained.

For me, this all comes back to my teacher's verbal instruction, that our experience of reality is an interpretation we make, and that Liberation (aka Enlightenment) is freedom from attachment to any single interpretation (or "view").

For 4. and 5. Yogacara of Svatantrika describes this to some extent. Storehouse consciousness (ālaya-vijñāna) always processes, even in sleep, coma or moments of death. It is the same source for scattered thoughts and appearances out of nowhere in waking state. It is just while sleeping, you don't have something that in Madhyamaka terms is called referential thing, which is a part of reality to reference. Therefore visions in dreams are completely illusive. You don't have too much control in this realm of sleep either - it's realm of "bubbling water", and bubbles are appearances of mind and mind is the source. It is true for mind-only school of Mahayana that the root of all appearances are karmic seeds from the past. As we know, cyclical presence of karmic imprints imply that Self view was not abandoned, and grasping is present.

In here also, mind-only schools claim that mind precedes and creates the body, you are not connected to the body in your sleep, yet mind creates some other body. In Vajrayana, for example, there is concept of Three Vajras; Mind, Body and Speech, but all of them are ruled and created by mind.

From Vajra Essence, essential text on Dzogchen in Nyingma tradtion:

Since I am unoriginated emptiness, the source of my origination is empty. As to seeking the source, earth is something I have created. Similarly, all phenomena, including water, fire, air, and space, are nothing other than apparitions of self-grasping

“I am the nonabiding nature of emptiness, so there is no place I dwell. As for the so-called body: Sores, swelling, goiters, ulcers, and so on may arise in the body that appears in the waking state, but they are not present in the dream body. And sores, swelling, goiters, and ulcers that appear to afflict the body and limbs in a dream are absent in the waking state. During the waking state, the body may be wounded or beaten as punishment by a king, but this does not appear on the dream body. If it happens in a dream, it is not present on the body in the waking state. Similarly, location, environment, and their possessor, whether they appear to be outside or are grasped as being inside, are all nothing more than my own appearances. “Therefore I do not abide in either external or internal phenomena, nor do external or internal phenomena abide in me. They are apparitions of self-grasping, like a magician’s illusion, but they are not created intentionally, as in the case of a magician and his magic. The self arises, so external appearances arise automatically, but they have no location. Even if you investigate the agent and the destination, the one who moves and the destination have no objective existence, so they do not go with the nature of me and mine.

For 1. and 2. As I have elaborated before, I can say that the experience of the body (and dream body) is the domain experience of the mind. All experience of the body within the dream is a sensation of the mind and comes from the mind. The body in the dream is a different body, it's health condition differs, et cetera.

If you're looking for effective practise, there is Dream Yoga and it's widely practised in Nyingma tradition of Vajrayana and generally speaking - all Dzogchen lineages. There are some people that teach it in non-sectarian way.