Music and dreaming are similar, because they both involve feelings in response to hypothetical situations. But they are different in various ways. Music may have evolved as a means to process feelings about hypothetical situations that dreaming cannot effectively process.

Definition of "Dreaming"

For the purposes of this article, when I talk about "dreams" and "dreaming", without any further qualification, I am referring to the dreams that occur during sleep.

The other kind of dreaming is daydreaming, which is also relevant to the subject of this article.

Similarities between Music And Dreaming

Music and dreams are similar, because they both involve, or can involve, the processing of feelings in response to situations that are not real, ie situations that are hypothetical. The processing of feelings often includes thought processes involved in deciding what a person would want to do in the situation in question.

In both cases, these feelings can be more extreme than might occur during most normal waking life.

The diagrams in my previous article Hypothesis: Music Lets Us Practice Feeling Strong Emotions illustrate this with reference to the emotional states invoked by music.

The interesting thing is that the same diagrams could be used to state a hypothesis about dreams. The only difference would be that the blue dots, instead of representing emotional states invoked by music, would represent emotional states invoked within dreams.

This similarity between music and dreaming suggests that music and dreaming may actually serve similar biological purposes.

To fully understand how this could be possible, we need to analyze all the differences between music and dreaming.

Differences between Music and Dreaming

Delusional and Non-Delusional

The default state of dreaming is a state of delusion. When a person is dreaming, the consciousness of the person within the dream believes that the dream is completely real.

As a result of this delusional state, the feelings from dreams can be very real. If you believe that you are being chased by a person who wants to murder you, then you will feel as scared as if a murderer was indeed chasing you in real life.

(The alternate non-delusional state of dreaming is Lucid Dreaming. This is an interesting topic in itself. However a degree of contrivance is usually required to achieve a state of lucid dreaming, and such attempts are often frustrated by changes in dreams that restore non-lucidity, such as dreaming that "you woke up". This is all consistent with the hypothesis that the biological function of dreams is best fulfilled under conditions of non-lucidity, ie delusionality.)

Music, on the other hand, does not create a delusional state.

This is especially evident if we consider maladaptive daydreamers, people who compulsively and intensively daydream, in many cases with music being both necessary and sufficient for their compulsive daydreaming to occur.

Even though maladaptive daydreamers report being unable to control their compulsion to daydream excessively, they never report entering a state of mind where they fail to recognize that their compulsive daydreams are purely fictional. In other words, they are never deluded.

Dreaming is Much Older than Music

There is considerable evidence that both mammals and birds experience dreams during sleep that are similiar to human dreams.

Music, on the other hand, seems to be limited to the human species, and is not found, as far as we can tell, in any other living species.

Also, some features of music seem to relate specifically to aspects of the perception of human speech, which adds to the evidence that music is something that evolved only on the lineage which led to modern humans, probably well after the point in time where human ancestors separated from the ancestry of any other living species (ie chimanzees).

The main conclusion to draw from this difference, if we assume that music and dreaming satisfy a similar biological purpose, is that music somehow extends the functionality provided by dreaming. For example, music might aid in the processing of responses to hypothetical scenarios, which for some reason, cannot be processed within dreams. (I will expand upon this idea later on in this article.)

Content and Emotions

Within dreams, the content and the emotions are provided as a single fixed package. The semi-conscious dreamer experiences the dream scenarios, feels emotions in response to the scenario, possible takes action required by the scenario (eg running away from the murderer), and that's it.

With music, the music itself generates the feelings, and any content is supplied separately.

Content can be supplied by various means, but there are three main sources in practice:

The lyrics of the song. Theatrical content supplied together with the music. (In modern times this is usually film or video, but of course these depend on recently developed technologies, and in the historic or prehistoric past any such content would have had to involve live acting of some kind.) The imagination of the listener.

The details of how the content and the emotions are associated are different in each case, and in the case of music it is possible to feel the emotions generated by the music without actually associating it with any specific content at all.

But, much of the time, the end result is the same – a hypothetical scenario is experienced, strong emotions are felt in relation to the scenario, and there may be consideration of what if any action to take in response.

Short-term and Long-term Goals

Dreams tend to involve scenarios where immediate action is required, in response to events and observations made by the dreamer within the dream.

Musically inspired scenarios tend to involve situations where changes have occurred which require the listener to think about how their decisions and strategies would change with regard to medium or long-term goals.

This difference may be directly relevant to explaining why music is human-specific – because actively thinking about long-term goals is (as far as we know) a specifically human endeavour.

A common aspect of dreams is that a dream contains some threat or other element requiring immediate reaction, and the dreamer reacts, and then another threat or element occurs, requiring further reaction, and the dreamer reacts, and so on.

There may be various reasons why dreaming is less effective for processing responses to hypothetical scenarios that require changes in long-term planning and strategy. For example, any drawn-out process of thought is more likely to be interrupted by the realisation that the dream is just a dream and the whole situation is hypothetical, and therefore does not really matter.

With music, the person is experiencing the music, and thinking about some hypothetical future scenario, and they already know that everything is hypothetical. That the person is aware of the fictional nature of the scenaro will limit the depth of feeling experienced, but at the same time the person can commit themselves to feeling the strength of feeling created by the music, and they will not be interrupted by realising something which they already know. (Of course there will be a sudden interruption if and when the music actually stops, and as a result there is a preference for the music to actually continue for a reasonable period of time.)

Altered Realities

Dreams can contain strange and altered realities. However dreams are never about the strangeness or the alteration of reality.

If people with bad intentions are chasing you in a dream, you don't start thinking about why your life changed so much that now you have people wanting to kill you. All you think about is what you need to do to prevent those people catching up with you and killing you, which might involve running, or attacking your attackers, or perhaps calling out for help.

Given that dreams are often seem very strange when we wake up and remember them, but don't "feel strange" when we are dreaming them, it is plausible to suppose that our sense of "strangeness" is actively suppressed when we are dreaming.

Music, on the other hand, can give rise to feelings which suggest a strange and altered reality.

In other words, musically-driven imagination can be "about" the strangeness of an altered reality.

This suggests the possibility that music evolved precisely for this reason – that it was desirable to process feelings about the strangeness of hypothetical altered realities, and the existing mechanism of dreaming could not do this, because any awareness of strangeness within a dream would lead the dreamer to consider the possibility that they were indeed in a dream, which would break the delusion.

Voluntary Movement

Dreams involve scenarios that require immediate response, which very often consists of actual behaviours, for example running away from someone trying to kill you.

Since dreams are delusional, it is important that the behavioural responses in dreams do not actually occur.

During REM sleep, REM atonia is a loss of muscle tone which prevents all bodily movement, expect for the eye movements (which are the "EM" in "REM"). Dreams can also occur during non-REM sleep, so presumably there are other mechanisms by which voluntary movement is suppressed during dreams.

Dream Enactment is what happens when responses to dream scenarios fail to be suppressed. This can occur briefly during the transition from sleeping to waking. It can also be made to occur in laboratory animals, for example by disabling brain activity which is responsible for the suppression.

With music, the scenarios are hypothetical, and the person listening to the music is not delusional, so they have no reason to engage in specific behaviours as part of the hypothetical scenario.

Nevertheless, depending on the genre and style, music is often accompanied by a non-specific desire to engage in some level of active behaviour. Because this desire is very non-specific, and because musical feelings are more strongly bound to things that match the rhythm and/or melody of the music, the end result is that the desire to engage in such activity can be satified either by dancing or by joining in with the performance of the music.

Dancing is not quite the same as doing nothing at all, however dancing tends to involve repetitive motions while moving a limited distance from the starting point, and in general the motions performed while dancing have no lasting consequence – so it's almost like doing nothing at all.

Conclusion: The Evolution of Music as a Supplement to Dreaming

The conclusion I draw from this analysis is that music evolved, sometime during the evolution of the human species, as a means of supplementing the functionality provide by dreaming.

With both dreaming and music, this functionality relates to hypothetical scenarios, and emotions felt in response to those scenarios, and decisions about what actions to take based on the details of the scenarios and the emotions felt.

The primary differences between music and dreaming, in relation to this proposed functionality, are:

The default state of dreaming is delusional, whereas musically-altered states of mind are always non-delusional.

Dreaming similiar to human dreaming occurs in other species, but music is very human-specific.

Dreams appear as a fixed package of content and emotion, whereas music supplies only emotion, which can then be reassigned to content supplied either with the music or by the music listener's own imagination.

Dreams relate more to situations where immediate action is required with respect to short-term goals. Musically-inspired thoughts relate more to situations where the overall situation of a person has changed in some significant manner, and changes are required related to medium or long-term goals.

Dreams occur with strange and altered versions of reality, but awareness of the strangeness is always suppressed while the dream is occurring, and dreams are never about the strangeness. Music, on the other hand, can be about the strangeness of an altered reality, and the music can inspire the listener to think about how they would act within such an altered reality.

the strangeness. Music, on the other hand, be about the strangeness of an altered reality, and the music can inspire the listener to think about how they would act within such an altered reality. Voluntary movement is almost completely suppressed during dreaming. The nearest analog in music seems to be that action is permitted, but the desire to act is satisified by dancing along with the music, and dancing appears to satisfy no purpose other than providing an outlet for the desire to do something while listening to music.

In my follow-up article The "World" Hypothesis I develop a more detailed hypothesis about the difference between what dreams are "about" and what music is "about".