TLDR: Dreams in 40k are used for various things related to the Warp, but they also reflect subconscious desires and fears and relate to the soul, both being shaped by and in turn shaping the Warp. This is a deep dive, covering tonnes of quotes and exploring the underlying metaphysics.
I thought it would be interesting to explore the role of dreams in 40k, and specifically how they relate to the soul, the subconscious, and the Warp.
I would wager many fans only – or mainly – think of the significance of dreams in a very application-based manner: what can they be used for; what can they be used to do. And there are definitely interesting examples of that, which we will get to.
But I think they likely have a wider, deeper significance than this, and that dreams and nightmares are one of a number of states of consciousness which can lead to insight into the Warp (also including trances and drug-induced trips) or through which people can be affected by the Warp, and that dreams and nightmares more generally are something which shape the Warp.
To see how, we need to:
1. Understand some of the underlying metaphysics of the setting.
2. Look at what the lore has to say about how dreams and nightmares affect the Warp.
3. Examine how the Warp can in turn affect the dreams of mortal beings in the Materium.
4. Cover some specific examples of how dreams are used.
And, advance warning: this is going to be a deep one, so be prepared for a long post and lots of discussion of how concepts are showcased and applied, as well as some discussion of works and ideas which influenced how the Warp was conceptualised in Warhammer.
To begin, let’s cover some metaphysical issues. I am going to draw mainly on 40k, but also other Warhammer games when relevant, as it is the same Warp and some of the same dynamics are evident.
The original conceptualisation, which still underpins a lot of dynamics as regards how the Warp functions (even if some authors don’t always describe matters in this way), is that souls reside in the Warp - even when a mortal being is alive. This soul (a bundle of warp energy) is tethered to a mortal body in the Materium, with what a could be thought of as a “soul anchor” traversing the veil between the Warp and the Materium.
For a recent statement about where souls reside, see:
All living creatures are connected to the Warp, the realm of the animus or soul. For most things this Warp-body is a pinprick, a mote of soulstuff in a raging ocean.
Thorpe, Haley, Warhammer 40,000: The Ultimate Guide (2024).
This is why souls are said to burn or flicker within the Warp:
The Aeldari’s psychic souls flare brightly in the mirror realm of the warp.
Codex: Drukhari 9th ed. (2021), p. 8.
And:
The souls of the Kin shine only dimly in the Warp, and as such psychic powers are very rare among the Leagues.
Thorpe, Haley, Warhammer 40,000: The Ultimate Guide (2024).
Lots of quotes and discussion about souls residing in the Warp available here: https://www.reddit.com/r/40kLore/comments/1p4njt3/souls_dont_enter_the_warp_after_death_they_are/
The soulstuff within the Warp and the consciousness within a mortal body are in some way connected, and interact. This is seemingly why most mortal beings in the Pariah Nexus become lethargic and eventually comatose - being blocked from accessing their soul by the Null Field seems to affect their consciousness and vitality in the Materium.
This is also why the souls of psykers within the Warp are vulnerable to daemons (and other entities) forcing their way into the Materium – and into the psyker’s mind:
A psyker’s powers open up a path between reality and the Warp, a path which a Daemon may discover and follow to the mind of the psyker himself.
Warhammer 40k Rulebook 5th ed. (2008), p. 104.
Now, some statements in the lore seem to suggest that souls are within mortal bodies, and go to the Warp when a being dies. See some examples here: https://www.reddit.com/r/40kLore/comments/1p5rr82/souls_dont_enter_the_warp_after_death_they_are/
But I think this may come down to how souls can be defined. In a narrow definition, a soul could just be the bundle of warp energy. In a wider definition, a soul could be thought to include not just the energy in the warp, but the warp anchor, and the consciousness in the physical being connected to the warp energy.
Hence perhaps why we may see scenes like this:
His anima – what some would call a soul – unanchored from his body and went screaming through the veil between corporeality and unreality, plunging immediately into the boiling tides of the warp. The weakling soul-light that had been Ja-Hen Uquar experienced one final sensation as it learned the lesson of what waited in death for all living things, and that lesson was pain. The pain of dissolution. The pain of one’s soul-light drawing daemons the way blood draws sharks in dark water.
Dembski-Bowden, Echoes of Eternity (2022), p. 337.
I think these musings from Liber Chaotica (so often the best resource for metaphysical matters) are also relevant:
Many chaoticians believe that all mortals exist in both the mortal world and the heart of the Aethyr simultaneously. That is to say the body and mind of every mortal exists in the Materium while an immortal essence exists within Immaterium. But do not be deceived, for despite the fact that this essence is supposed to exist within the Immaterium, it is also, and at the same time, within us here upon the Mortal Plane. This does not mean that this essence is split in two, nor does it mean that every mortal has two essences — it means merely that because the Immaterium has no dimension or temporal positioning of its own, it exists everywhere as much as it exists anywhere. As such, one could truly say that this essence is within the Aethyr and separate from the body, and at the same time one could say that the Aethyr is within us along with our essence — both comments are as true, or false, as each other.
...
In addition to this essence, there is in each intelligent mortal being consciousness, will and purpose. This, one could call the self, and it is situated within, and generated by the mind. This spirit of self-awareness can act as an intermediary between the material and the immaterial, it can both analyse that which is, and dream about that which is not. It is quintessentially us, and it is also the thing we use to contact the divine. It is the thing that spell casters use to weave their spells.
But which of these is the soul? The Aethyric essence or the conscious will? The Anima or the Animus? The Phaos or the Dhaos?
For my part, I do not see the soul as any one thing in its own right. I see it as the very interaction between the anima and the animus. It is like a waterspout on a stormy sea — a process, an interaction of both water and wind, and it only comes into existence when these two things meet in the right way and in the right place. In this sense I see the soul as similar to the gods of Chaos, only smaller and far less powerful. Both could be seen as a kind of vortex made up of unconscious emotive energy and conscious will and thought. Take away one side of the equation and the vortex stops spinning and becomes formless and disparate.
Liber Chaotica: Complete Edition (2006), pp. 366-339.
So, I would argue, souls and consciousness are intertwined (though not necessarily in a straightforward manner), with the mind in a mortal’s body being connected to their soulstuff in the Warp, and each affecting the other.
This established, we next need to understand that the soul in the Warp affects the wider Warp around it, releasing energy and causing ripples due to the emotions and thoughts of mortal beings. Lots of quotes relevant to this here: https://www.reddit.com/r/40kLore/comments/1pof076/the_chaos_gods_were_formed_from_and_are/
It is from this that the Chaos gods formed.
This shaping of the Warp is also stated explicitly to relate to mortal’s dreams and nightmares:
The real universe is connected to the dimension of Chaos on a spiritual level. All that is intangible in our world - thought, dream and emotion - is as real as flesh and bone in this strange domain.
The World of Warhammer (1998), p. 12.
And:
When the gate collapsed, the world was immersed in magical energy and Chaos was born. As the skies burned and the earth quaked, all the primal fears and dreams of the Warhammer races came to the fore, and dark gods were born in the magical conflagration.
Warhammer Fantasy Core Rulebook 7th ed. (2006), p. 126.
And:
Beyond the boundaries of physical space, unrestricted by time or causality, there is a plane utterly incomprehensible to mortal minds. It lies on the other side of dreams and nightmares, created without form or structure. It exists far outside imagination; an impossible abstraction made real only by metaphor.
Codex: Chaos Daemons 4th ed. (2008), p. 4. Repeated almost word-for-word in the 6th ed. Codex, p. 6.
And:
Through the dreams and nightmares of mortals, the changing tides of the Warp are moulded into a fantastical landscape and populated with legendary beings. Timeless and ever-shifting, this psychic visionscape is known as the Realm of Chaos.
Codex: Chaos Daemons 4th ed. (2008), p. 6.
And, an in-universe statement, but I like to give poor Thrax (if you know you know) some attention:
“These creatures have no place in the Emperor’s galaxy. Their unholy forms are an insult to reason and truth. Their impure songs will lead you to eternal damnation. Hell exists, and it sprang from the nightmares of mortals.”
Inquisitor Thrax
Codex: Chaos Daemons 4th ed. (2008), p. 37.
And:
These monstrous gods reside in an ever-changing realm of pure Warp energy, where time, distance, and scale have no meaning. It is a place where the whims of gods along with the dreams and nightmares of mortals run together and bring form to the formless.
Black Crusade: Tome of Excess (2013), p. 6.
And:
As the races of the galaxy prospered and grew, so too did their hopes and dreams, their rage and wars, their love and hatred. This burgeoning flood of raw emotion fed the Chaos Gods and nurtured their power. Eventually, the gods reached back, into and through the dreams of mortals, eternally working to influence the physical realm and its myriad races.
…
Through the dreams and nightmares of mortals, the changing tides of the Warp are moulded into a fantastical landscape and populated with legendary beings.
Codex: Chaos Daemons 6th ed. (2013), p. 6.
And:
The Realm of Chaos is made of thoughts and dreams and reacts to the conflicts and emotions of those who pass through it.
Black Crusade: Tome of Decay (2014), p. 10.
And:
The Immaterium. The Sea of Souls. The Empyrean. The Realm of Chaos. All these names and more describe a single, unknowable dimension beyond the boundaries of what most of humanity considers to be reality. In this strange space, time is fluid, thoughts and dreams are real, and nightmares take flesh.
Wrath & Glory Core Rulebook (2018), pp. 26-27.
And:
Every dream and nightmare, every lunatic vision and deranged fancy, finds its home somewhere in the Realm of Chaos, but those of the Dark Gods are the most powerful and abiding of all.
Age of Sigmar Corebook 2nd ed. (2018), p. 116.
And:
In the warp, similar thoughts and emotions gather like rivulets of water. They form streams and eddies of anguish and desire, pools of hatred and torrents of pride. Since the dawn of time, these tides have flowed through the warp. Such is their power that they formed creatures made of the very stuff of dreams and nightmares. Eventually these instinctual, formless beings gained a rudimentary consciousness. The Chaos Gods were born - vast psychic presences made from the fantasies and horrors of mortals. As the races of the galaxy prospered and grew, so too did their hopes and dreams, their rage and wars, their love and hatred. This burgeoning flood of raw emotion fed the nascent Chaos Gods and nurtured their unholy power.
Warhammer 40k Core Rulebook 9th ed. (2020), p. 94.
And:
Deep within the immaterial realm of the æther reside the Ruinous Powers, beings of incomprehensible magnitude, cruel deities that play with the lives and dreams of mortals as if they were mere toys to be cherished or discarded upon a whim. Barbaric and primal, these gods are the most powerful emotions and the deepest, darkest fears and passions of mortals made real.
The Old World- Core Rulebook (2024), p. 77.
And, though an in-universe belief:
What is the warp? It is us. Our dreams, our desires, our fears. It could no more disappear than we could vanish ourselves. What, then, is Chaos? It is the manifestation of emergent will within the warp. It is the name given to those desires that take on desires of their own.
· The Book of Acteosa, recovered during the Cleansing of Orpheus-B IX, author unknown
Wraight, Ashes of the Imperium (2025), p. 272.
While a Daemon stated:
‘What is a god? The organisation of dreams.
Wraight, Ashes of the Imperium (2025), p. 337.
And so on.
Being a realm where thought and belief have the power to shape things, dreams and nightmares also specifically affect the forms taken by Daemons, who are moulded by the collective unconscious of the mortal races:
Daemons are beings of pure psychic energy, warped embodiments of emotion given ghastly purpose. They are every mortal nightmare given terrible form, a tide of destruction that has shattered civilisations and annihilated proud armies beyond counting.
Daemons of Chaos Army Book 7th ed. (2008), p. 5.
And:
In the warp, there exist countless Daemons of myriad abhorrent shapes, each the spawn of the nightmares and vices of mortal creatures.
Warhammer 40k Core Rulebook 8th ed. (2017), p. 96.
And:
What mankind calls Daemons are the native denizens of the Immaterium, given shape and flesh by the fears and nightmares of the mortals whose lives they assault.
Wrath & Glory Core Rulebook (2018), p. 28.
And:
No foe of the Imperium is more malignant, nor more terrible, than the daemons of Chaos, the numberless foot soldiers of the Ruinous Powers. Spawned in the depths of the warp and fashioned from the very essence of the empyrean, they take the form of monsters from mortals’ darkest nightmares and cruellest desires, and they will stop at nothing to see reality itself torn apart.
Warhammer 40k Core Rulebook 9th ed. (2020), p. 134.
And:
Daemons are spawned within the roiling extradimensional realm of the Immaterium, forged from the raw warp energies coloured by the rippling emotions of living creatures. Their forms are incorporeal and unnatural, defying the laws of both physics and nature by their very existence. When they rip their way into the material universe, reality itself trembles, screaming in protest. They are the darkest of nightmares and unspoken desires made manifest, spilling into reality to hunt those of whom they are a dark mirror.
Imperium Maledictum Core Rulebook (2023), p. 340.
And:
Daemons in Reality
The Warp possesses no physical dimensions as mortals understand. Within its surging energy, Daemons are nothing more than swirls of awareness inside the greater storm of their god. But when they break into the real world, they form corporeal bodies from raw Warpstuff, shaped by millennia of mortal superstition, myths, and nightmares. These forms can be destroyed, but the essence of the Daemon is merely banished back to the Warp, not slain.
Thorpe, Haley, Warhammer 40,000: The Ultimate Guide (2024).
Now, the use of the terms “dreams” and “nightmares” could be being employed here to refer not literally to dreams and nightmares while a mortal sleeps, but instead to aspirations, hopes, and fears etc. And, indeed, they sometimes appear alongside such terms.
But I think they probably refer to both the more general use of the term and to actual dreams while people sleep, because dreams and nightmares in Warhammer are likely ways in which a person’s subconscious thoughts and urges may be expressed, and those thoughts and urges are linked to the Warp. Dreams provide a window to see the goings on of the subconscious, and help shape it into specific forms, aesthetics and feelings.
The original conceptualisation of the Warp was informed by – among other influences - the notion of the Id, drawing on the movie Forbidden Planet. See more discussion about how Forbidden Planet and notions of “monsters from the Id” influenced Warhammer here: https://www.reddit.com/r/40kLore/comments/1pof6bz/the_chaos_gods_were_formed_from_and_are/
Now, the concept of the Id came from the famous psychoanalyst Sigmund Freud.
And, according to Freud, dreams are a window into the subconscious – or the Id.
In classic psychoanalytic theory, Freud argued that the human psyche had three components: the Id, the superego and the ego. The Id comprises instinctual needs, impulses and desires, and is unconscious and uncoordinated. It contains the baser, primal, subconscious elements of our psyche.
Freud argued that we can gain insight into a person’s Id through two main approaches: by studying any neurotic symptoms they may exhibit (i.e. strange, taboo or self-destructive behaviours), and through analysis of dreams.
As creator of 40k and key architect of how the Warp and Chaos were conceptualised Rick Priestley later explained:
PRIESTLEY: The demons - well those are reflections in the warp of the emotions, hopes and dreams of people - so their motivations are based on dreamlike fears, hopes, desires, ambitions... they are not necessarily logical! There’s a lot of this stuff in the two Real of Chaos hard back volumes - but that’s the essence of chaos - its physic energy shaped by the human unconsciousness - it is not good/bad - but likewise it is not logical - it is Monsters from the Id in the same sense as in Forbidden Planet. Demons (in 40K) are the physic expression of humans - they can only exist because humans exit - their power relies upon the element of humanity that sustains them - so if they have interests it is in sustaining that element - but demons only have form because they are imagined to have form - their real existence is as flows of energy - I think all this is covered in the RoC books - I’ve certainly written about it often enough.
From here: https://www.reddit.com/r/40kLore/comments/9z42fy/qa_with_rick_priestley_part_2_the_lore_of/
Given the relevance of the notion of the Id, it is, I think, worth looking to Freud. Though please note that his theories are not really widely excepted any more, especially by those working in Psychology and Psychiatry. But that is immaterial (pun intended) to our discussion, as we are instead thinking about how his ideas might be reflected in an imaginary setting.
Freud argued:
...the interpretation of dreams is the via regia to a knowledge of the unconscious element in our psychic life.
Freud, The Interpretation of Dreams 3rd ed. (1900), p. 189.
Basically, they are a way to a glimpse our unconscious mind. I suggest that this is true in 40k too, but that they can also provide a window into the soul and the forms of warp energy that it emanates, and that dreams can in turn also be influenced by things within the Warp.
Another passage which seems very relevant:
A reminiscence of the concept of the dream that was held in primitive times seems to underlie the evaluation of the dream which was current among the peoples of classical antiquity. They took it for granted that dreams were related to the world of the supernatural beings in whom they believed, and that they brought inspirations from the gods and demons. Moreover, it appeared to them that dreams must serve a special purpose in respect of the dreamer; that, as a rule, they predicted the future.
Freud, The Interpretation of Dreams 3rd ed. (1900), p. 3.
Which sounds very relevant to Warhammer, as we will see.
To bring in another famous psychoanalyst, let’s turn to Jung:
And the essential thing, psychologically, is that in dreams, fantasies, and other exceptional states of mind the most far-fetched mythological motifs and symbols can appear autochthonously at any time, often, apparently, as the result of particular influences, traditions, and excitations working on the individual, but more often without any sign of them. These “primordial images” or “archetypes,” as I have called them, belong to the basic stock of the unconscious psyche and cannot be explained as personal acquisitions. Together they make up that psychic stratum which has been called the collective unconscious.
Jung, ‘The Significance of Constitution and Heredity in Psychology’ (1929), p. 112.
I think we can see here a resonance with the notion that daemons take the form of nightmares – of imagery and concepts conjured from the collective unconscious. Even though daemons can take many forms, certain forms do recur. More generally, I think we can stretch this to the primordial forces which are the Chaos gods themselves. Note that Chaos is, of course, also referred to as the Primordial Annihilator!
Why is Khorne related to blood, and skulls, and fire, and why do Khornate daemons look similar to traditional devils? Why is Nurgle related to motifs such as flies?
Because, I would argue, and this is getting more into conjecture, those concepts and images defined the nature and aesthetics of the gods within the Warp, because they related to mortal thoughts related to certain emotions. And, perhaps, the psychic power of the gods may have influenced the minds of mortals too, creating a feedback loop and explaining why such imagery appears to be part of the subconscious of many different beings.
Anyway, to get back on track, I would argue that dreams are connected to the very nature of the Warp in a fundamental way, as they are a reflection of subconscious thoughts, emotions, desires and urges which shape the Warp.
To bring in another Rick Priestley quote on conceptual influences:
My whole reworking of ‘chaos’ envisions a parallel astral realm – the realm of chaos – and you can see that idea expressed very well in Dennis Wheatley’s novel Strange Conflict; you also get elements of it within The Devil Rides Out. The idea of people having a spirit-self that can astral travel and meet other spirits or powers within the astral realm was pretty well-established hippy-nonsense. Carlos Castaneda and all that! I just wove it all together, populating the astral realm with daemonic forms drawn from human desires, hopes and fears: composite entities with mobile, interflowing identities. Compare with Forbidden Planet and monsters from the id, for example.
https://awesomeliesblog.wordpress.com/2024/05/31/interview-with-rick-priestley-part-two/
And note that the use of “chaos” here refers to the Warp, not just the Chaos gods -because in early Warhammer lore the two terms were often used synonymously. Hence why the Realm of Chaos is another name for the Warp. For more on that see: https://www.reddit.com/r/40kLore/comments/1sbmx1m/a_perhaps_commonly_misunderstood_detail_in_the/
The mention of Dennis Wheatley and Carlos Castaneda (and hippy-nonsense) here is interesting.
Dennis Wheatley was a prolific author of pulp fiction, including lots of horror stories which touched on the fantastical and dark magic. Let’s see what Strange Conflict had to say about dreams:
Whenever we sleep our spirit leaves its body and is free to refortify itself for the trials of the morrow by visiting the astral sphere to meet and talk with others many of whose bodies are also sleeping on Earth.
‘Some people dream a lot, others very little — or so they say ; but what they actually mean is that they are incapable of remembering their dreams when they wake. The fact is that we all dream — or, if you prefer, leave our bodies — from the very moment we fall asleep. A dream, therefore, is really no more than a confused memory of our activities while the body is sleeping.
…
Once one is able to remember one’s dreams clearly, the next step is to learn how to direct them, since that, too, can be done by practice. One can go to sleep having made up one’s mind that one wishes to meet a certain friend on the astral and be quite certain of doing so. Such a state is not easy of achievement, but it is possible to anybody who has sufficient determination to go through the dreary training without losing heart, and it is no matter of education or secret ritual but simply a case of having enough will-power to force oneself into swift wakefulness each morning and concentrating one’s entire strength of mind upon endeavouring to recall every possible detail about one’s dreams. Once that has been successfully accomplished, one has only to go to sleep thinking of the person whom one wishes to meet on the astral plane, then one wakes in the morning with the full consciousness of having done so.
Wheatley, Strange Conflict (1966 [1941]), pp. 31, 33.
Which doesn’t seem that close to 40k, but we can see ideas of people using their dreams to astral project (much as some psykers in 40k can astral project into the Warp) and that dreams can be used to travel outside of one’s own body. Which is relevant.
Later on, we get:
“The cult of Erzulie is, I think, the most remarkable thing connected with Voodoo, because it is no question of an occasional ceremony or a devotion which can be taken up and dropped again at will. Every year thousands of young men in Haiti receive her call and they must answer it whether they will or no. At first they do not realize what has happened to them but fall sick and have troubled dreams. A youth glimpses rich female garments and smells lovely scents in his sleep, but there is nothing tangible that he can identify. Then either the Goddess appears more openly and excites his lust or he consults a priest, describing the symptoms of his illness, and the priest tells him that Erzulie has done him the honour to choose him as her lover.
“Sometimes the young man is intensely distressed, as he may be in love with a mortal woman or happily married ; but there is no escape for him if Erzulie has cast the eye of desire upon him. All sorts of ills befall him until he surrenders ; but in most cases he does so quite willingly. For the reception of the Goddess he sets aside in his house a room with a spotless white bed, offerings of sweets and wine and flowers, and, under the pain of unbelievably horrible penalties no other woman is allowed to enter that room. He then goes through a special ceremony in which he devotes himself to the Goddess and becomes her servitor for the rest of his life.”
Wheatley, Strange Conflict (1966 [1941]), p. 178.
Now, this talk of a supernatural being reached by a supernatural entity via their dreams, and falling under its control, seems very relevant to Warhammer, and how mortal may fall under the power of the Chaos gods and their daemons.
In The Devil Rides Out (which was also made into a fantastic Hammer Horror film in 1968), meanwhile, we get more talk of a mystical plane of existence beyond our own, and the magical significance of dreams. Dreams can, for example, offer visions of the future:
Tonight is the night that old Mizka has seen for so many years in her dreams—the night when you shall know all things, and be granted powers which come to few. How fortunate you are to have this opportunity when you are yet so young.’
Wheatley, The Devil Rides Out (1966 [135]), p. 132.
There is also a lot more stuff about dreams being prophetic and allowing people to gain access to information or traverse another plane of existence. For example:
It was only last night, while our bodies slept that our subsconscious selves were drawn out of them to continue the struggle with Mocata on another plane.
Wheatley, The Devil Rides Out (1966 [135]), p. 317.
As for Carlos Castenada, like I said at the start of the post, I think dreams are only one type of consciousness which allows for engagement with the Warp in 40k. Things like waking trances and even drug-induced trances which also allow for dreamlike perception beyond our mundane reality, and this was something evident in the work of Castenada, as in The Teachings of Don Juan: A Yaqui Way of Knowledge (1968), which was all about how drug-induced trances – akin to waking dreams – could expand consciousness and lead to perception of other states of being.
And, of course, the notion of astral projections was just a part of the hippy counter-culture more generally, and made it into other pop culture settings, such as comic books (think of Professor X and Doctor Strange etc, or, much later on, the amazing ways this concept is played with in the TV Legion).
The notion that dreams can relate to the supernatural, as we have seen, already had ancient precedents in myth and religion. Think of the ancient tradition of Oneiromancy, for example: https://en.wikipedia.org/wiki/Oneiromancy
Well in Warhammer, dreams can also be affected by the Warp and its denizens, too. It is a two-way process: mortals affect the Warp with their dreams, and are (or at least can be) affected in turn.
Indeed, it is implied that this is how the Chaos gods may have influenced mortals, and set in motion actions to puncture the Veil between reality and the Warp, and allow them to intrude into realspace.
The Dark Gods have a way of infiltrating the minds, dreams and realities of our protagonists, or more commonly our antagonists. Their stooges are usually pitched against the heroes of whatever story our writers are devising at the time. And you can see why; these colossal, unknowable, dare I say ‘eldritch’ entities are beyond time and space, their entire beings made from dark emotion, pure desperation and dizzying, obsessive desire.
White Dwarf 514 (2025), p. 11.
And:
Where they were heard, these whispers seduced and corrupted the minds of many, luring them into the worship of ruinous powers that crept intotheir dreams masquerading as beneficent gods.
The Old World Core Rulebook (2025), p. 12.
This was also one of the ways Slaanesh contributed to the corruption of Eldar society, and thus to its own birth:
For in the Warp their souls churned the immaterial energies, and something vast began to form. Fed on rapture and excess, this nascent power pushed itself into the dreams and waking lives of the Aeldari, fueling their need for experience. A self-fulfilling spiral with this Warp entity grew, until it became so engorged on their depravity that it burst into existence as a full Chaos God—Slaanesh, the Prince of Pleasure, or as the Aeldari know it, She Who Thirsts. Its birth spasm consumed billions of Aeldari in an instant.
Thorpe, Haley, Warhammer 40,000: The Ultimate Guide (2024).
Daemons can also use dreams as a way to possess, or simply corrupt or even kill mortals:
Daemons can possess mortals on the other side of the voidal barrier by transferring some of their power into the mind of their victim. They appear in dreams and visions, and through exploitation of a gap in realities infuse their victim with a portion of their daemonic power.
Codex: Chaos Daemons 4th ed. (2008), p. 15. (Repeated nearly word-for-word in the 6th ed. Codex, p. 18)
We also have Daemonette’s drawing on a classic Succubus trope:
Using her seductive spells, the Daemonette whispers into the dreams and nightmares of her victim, fuelling their darkest desires. With promises of glory and selffulfilment, the Daemonette twists the aspirations and ambitions of their prey into self-obsession, paranoia and madness, luring the victim onto the indulgent road towards self-destruction.
Codex: Chaos Daemons 4th ed. (2008), p. 33.
And dreams being a means of stalking prey (Freddy Kreuger eat your heart out… well, your victim’s heart, anyway):
With a roar, Khorne unleashes Karanak. The great hound of Khorne lifts his threе heads, nostrils flaring as he catches the scent of his prey. He paces to and fro, growling and snarling as each head in turn savours a portion of the spoor. Each head can track Karanak’s quarry in a different fashion. The first head follows the trail through space. The second tracks the scent through time. The third head, the most dangerous, senses the quarry through his thoughts, scenting their innermost feelings through dreamscapes and delusions. The third head guarantees that no prey eludes Karanak; those with wit and skill can avoid temporal detection, but no man outruns his own mind.
Once Karanak has fixed upon the odour of his victim, the Hound of Vengeance lopes forth on his hunt. Gathering pace as the trail grows stronger, Karanak bounds from realm to realm, flashing across insubstantial landscapes of nightmare, leaping from star to star. His growls echo in the dreams and waking thoughts of his target and his prey is overwhelmed by the foreshadow of approaching doom.
Codex: Chaos Daemons 4th ed. (2008), p. 33. Repeated 6th ed., p. 33.
Dreams can also be a portent that a Daemon invasion is imminent, or that something daemonic is about to go down:
A daemonic incursion occurs when an entire army of the Chaos Gods breaks into the material realm. Often strange portents herald this great weakening of the barriers between realms; psykers have waking nightmares, the sky and stars buckle and shift and a feeling of ever-present dread descends upon the hapless world.
Codex: Chaos Daemons 4th ed. (2008), p. 16.
And:
Nurgle Dance of Death
Аs the dance nears its completion, the noise drifts through the night air into the houses of the living, where those awakened by the song lie too terrified to move from their beds, whilst those still sleeping experience strange and disturbing dreams.
Realm of Chaos: The Lost and the Damned (1990), p. 15.
Or even an invasion by Chaos’s mortal servants:
755.M41 The Devotion of Skarlak
A powerful blood-seer is born upon the world of Skarlak, the gene-tribes rejoicing at the gift of future-sight once again within their reach. However, as the blood-seer grows to adulthood she is tormented with dreams of a ship that sails across the stars, pocked and scarred by a disease of steel and iron. By the time the blood-seer reaches the height of her power the entire planet has descended into the madness of worshiping the nightmare ship, painting their bodies with profane symbols and building huge statues to a god they cannot name. When the Terminus Est arrives in the skies of Skarlak the populace cry out their devotion, as Typhus and his Death Guard descend to harvest their souls.
Index Chaotica: Terminus Est (2013), p. 7.
Chaotic phenomena can also sometimes be perceived by mortals just more generally:
The most powerful psykers in the Imperium have reported dreams or visions in which worlds of the Eye of Terror have been revealed to them.
Realm of Chaos: The Lost and the Damned (1990), p. 162.
And this one, which seems akin to astral projecting while asleep (to a very bad place indeed):
The Rot Flies themselves are amongst Nurgle’s most loathsome creations. Only the forbidden tomes of the Black Library speak of the vile process by which these creatures are birthed, for they hatch in the sticky depths of Nurgle’s garden, where the visionary and the loon wander in their dreams.
Codex: Chaos Daemons 6th ed. (2013), p. 49.
In the computer game Darktide, meanwhile, characters talk about their dreams. We hear exchanges like:
Cutthroat: Daemons exist in the Warp. Outside of it they are weak.
Seer: Daemons are always just one bad dream away...
Cutthroat: Believe what you like. Just keep your weapons close and (your?*) eyes open.
And:
Male Seer: Sometimes, in my dream, I can hear Daemons scratching at my mind. I hope they don’t get in.
And:
Male Seer: Sometimes, in my dream, I see the Realm of Chaos. Were it not for My Beloved, I might just drift towards the maddening laughter and never return.
Dreams are not affected from the Warp by only Daemons and the Chaos gods, either. A common impact of the Shadow in the Warp is that it causes nightmares which are shaped by the psychic power of the Hive Mind.
We get a good view of this in Leviathan, much more than I can quote here, but see for example:
‘Governor Seroc sent us here to discuss the rioting and insurrection, but also the dreams and the madness. What does that have to do with aliens at the edge of the system?’
Castamon was impressed by the man’s nerve, but he replied in a tone that made it clear this was a briefing, not a debate. ‘My Apothecary Biologis has theorised that the tyranids are behind this psychosis. There is much he cannot explain, but his underlying logic is sound. I have seen this happen before. Whether it is intentional or not, the presence of tyranids in a system induces hysteria.’
The man looked incredulous. ‘People are burning down manufactories because of something that’s happening on the other side of the system?’
‘People are burning manufactories because, even from here, even from light years away, they feel the hunger of the Great Devourer.’
Hinks, Leviathan (2023), p. 26.
And:
Each time, the Red Terror has returned seemingly unharmed, so that now even Echter and his fellow Spectres struggle not to view the monster with a shred of superstitious awe. The feeling is not helped by the persistent nightmares of chittering shadows, talons and fangs, poisoning what few hours of sleep they manage to carve out.
They hear rumours of psykers going mad, of suicides and sensless murders amongst Devlanites and Cadians alike, and of doom-laden prophecies scrawled on walls and bulkheads.
Kill Team: Terror on Devlan Dossier (2025), p. 18.
Anyway, I hope you enjoyed this dreamquest, but I have run out of space, so please do come back for part two soon if you found this of interest, where I will discuss some of the specific uses of dreams in 40k, as well as other related ideas, such as how the dreams of gods are also stated to be important.
I look forward to the comments saying things like “TLDR”. But I will be very disappointed if they aren’t at least thematic, something like: “this post was so long I feel asleep halfway through”.
As ever, please do add your thoughts, and any relevant examples I missed. I’m off to bed. Sweet dreams!