Why do we dream? The honest answer is that no one knows for certain, but three traditions have offered serious answers, and they disagree in ways that are more useful than any single verdict. Freud's is the most famous and the most contested. Artemidorus and Ibn Sirin, working centuries earlier and in very different worlds, asked a related but distinct question: not why the mind produces dreams, but what a particular dream means for the person who had it. The research that exists supports some of their assumptions and undercuts others. None of the three can be called correct.
Freud's answer: the dream as a disguised wish
In The Interpretation of Dreams (1900), Freud argued that every dream is the fulfilment of a wish. Not a straightforward one. The wish is usually unacceptable to the waking mind, so the dream disguises it. What the dreamer remembers on waking, the manifest content, is a cover story. The latent content, the real wish, has been transformed by condensation (one image carrying several meanings), displacement (feeling moved from the important object to a trivial one), and secondary revision (the mind tidying the story as it is recalled). The dream is a compromise between the wish and the censorship that forbids it.
This is a theory of why we dream, not just what dreams mean. For Freud, dreaming protects sleep. The wish is allowed a partial, disguised expression so that the sleeper is not woken by it. The dream is a guardian of rest.
Where Freud now looks wrong is in the claim that every dream is wish-fulfilment. Even sympathetic readers have found dreams of punishment, anxiety and trauma difficult to fit. Freud himself acknowledged that some dreams seem to contradict the theory and argued they were exceptions that proved the rule. That move convinced his followers and not many others. The Interpretation of Dreams remains a serious book, but its central claim is not supported by later research in the way its author hoped.
Artemidorus: the dream as a practical forecast
Artemidorus of Daldis, writing in Greek in the second century CE, compiled the Oneirocritica, the most complete dream manual surviving from antiquity. He was not interested in hidden wishes. He was interested in outcomes. He distinguished the oneiros, a dream that bears meaning about what is to come, from the enhypnion, a dream that merely reflects the dreamer's present state, such as dreaming of food when hungry. Only the first kind required interpretation.
His method was empirical and situational, closer to a field researcher than a mystic. A symbol's meaning depended on the dreamer's trade, status, health and habits. The same dream could mean different things to a sailor and a magistrate. Artemidorus collected and compared reports, and he was explicit that interpretation was a matter of probability, not certainty.
The contrast with Freud is sharp. Freud looked backward, to a childhood wish. Artemidorus looked forward, to a likely event. Freud treated the manifest content as a disguise. Artemidorus treated it as the substance of the forecast. Both were systematic. Neither was right in the sense a modern reader might want.
Ibn Sirin: the dream as a conditional sign
Ibn Sirin was born in Basra and died in 728 CE, living under the Umayyads. He was a tabi'i, of the generation after the Prophet's companions, and is remembered as a jurist and traditionist. The tradition of ta'bir associated with his name is conditional and morally attentive. Interpretation is analogy, not knowledge of the unseen, and the interpreter is warned against certainty.
Many works circulating under Ibn Sirin's name were compiled long after his death, so it is more accurate to speak of the tradition associated with him than of his own book. That tradition treats dreams as signs that may be read, but always within limits. A dream of water might be read as mercy, but the reading depends on context and character, and the interpreter does not claim to know the decree of God. This is a living religious tradition, not folklore, and it should be treated with the seriousness it commands.
The contrast with both Freud and Artemidorus is considerable. Freud's dream is a private wish. Artemidorus's dream is a practical forecast. Ibn Sirin's dream is a conditional sign, morally significant and never a certainty.
Where the three disagree, and why that matters
Freud and Artemidorus disagree about time. Freud's dream points to the past, to a wish already formed. Artemidorus's dream points to the future, to an event not yet decided. Ibn Sirin would not accept either framing without qualification, because for him the dream is a sign to be read with humility, not a mechanism or a forecast.
They also disagree about the dreamer. Freud's dreamer is a patient, whose history holds the key. Artemidorus's dreamer is a social actor, whose trade and status shape the meaning. Ibn Sirin's dreamer is a moral agent, whose character affects how the dream should be understood. Each tradition gives the dreamer a different role in the interpretation.
A dream is not a text with one correct reading. It is a human event, and the traditions that have taken it seriously have disagreed about what kind of event it is.
The disagreement is not a failure of scholarship. It is the reason the question remains alive. A single answer would be tidier. It would also be less true to the evidence, which is fragmentary and contested. Researchers still disagree about the function of dreaming, and the traditions disagree about its meaning. Neither disagreement is likely to be resolved soon.
What the research supports, and what it does not
Modern research on dreaming is not settled, and it would be dishonest to pretend otherwise. The evidence supports some claims more than others. Sleep and dreaming are clearly connected, and the discovery of REM sleep in the twentieth century gave the study of dreams a physiological basis that Freud did not have. But the idea that REM sleep is the same as dreaming has been challenged, since dreaming can occur outside REM and REM can occur without reported dreams.
The claim that dreams serve a specific function, such as memory consolidation or emotional processing, has been widely proposed and remains debated. Some studies support a role for sleep in memory, but the role of dreaming itself, as opposed to sleep more generally, is much less clear. The claim that dreams are disguised wishes, in Freud's sense, has not been supported by research in the way his followers hoped.
What the research does support is the importance of the dreamer's context. Artemidorus would have recognised the finding that dream content reflects waking concerns and circumstances. That is not a vindication of his method of interpretation, but it is a point in his favour.
What to do with the question
The question why do we dream has no settled answer. Freud gave one, and it was influential, and it is probably wrong in its strongest form. Artemidorus gave another, and it was practical, and it is not a science. Ibn Sirin gave a third, and it was conditional, and it is a religious tradition that deserves respect rather than dismissal.
The dream you woke up with this morning is not a puzzle with one correct solution. It is a human event, shaped by your life, your concerns and the traditions you happen to find useful. The three traditions offer different kinds of reading, and none of them can tell you what will happen. What they can do is give you a way of thinking about the dream that is more interesting than a dictionary definition.
If the dream was distressing, especially if it recurs or involves waking in fear, a professional is the right address for it. That is not a failure of interpretation. It is a recognition that some dreams are not for reading.
For the dream you had last night, the one that stayed with you, the three traditions each have something to say. They will not agree. That is the point.