There are many different theories about why we dream, but of all of them, Sigmund Freud’s has proven to be the most provocative.
In his Interpretation of Dreams published in 1900, Freud proposes that dreams express the fulfilment of our wishes. We all have various needs and desires, says Freud, and when these arise during the night and threaten to interrupt sleep, we instead dream of fulfilling them through a hallucinatory experience of satisfaction. In this way, dreams, says Freud, act as the guardians of sleep.
At first glance, Freud’s theory appears patently absurd. Often the most memorable dreams—nightmares—appear to be anything but the fulfilment of wishes! They even wake us up! However, Freud believes that nightmares even satisfy our desires, but just not the ones that we admit to ourselves. For example, “improper” impulses of sexuality and aggression, censored by our moral inclinations, may find distorted form in our dreams.
Through interpretation, then, dreams possibly provide the “royal road to the unconscious” (a phrase coined by Freud), allowing insight into the hidden recesses of our personality.
However, in the early 1950s, various stages of sleep were discovered, including rapid-eye movement (REM) sleep. REM sleep occurs in roughly 90-100 minute cycles, increasing in frequency towards morning. While the earlier stages of sleep are characterised by deeper sleep and slower brain activity, REM sleep is described as paradoxical sleep because the brain is highly active and resembles being awake. There also appears to be an intimate relation between dreaming and REM sleep. Most (up to 95 per cent) of people report dreaming if awoken during REM sleep, whereas only 5-10 per cent do during the other sleep stages.
The dream-REM sleep association led critics to declare that Freud’s theory is clearly false: REM sleep is activated by cyclical brainstem activation and unconnected to motivational states. Dreams simply represent random, meaningless imagery and hyper-emotionality.
However, the story is not so simple. Individuals who are incapable of REM sleep due to brain-stem lesions still report dreaming. Instead, loss of dreaming appears associated with damage to the brain’s mesolimbic-mesocortical dopamine pathway.
The mesolimbic-mesocortical dopamine pathway is associated with motivated behaviour, desire, and appetitive interactions with the world.Thus, this dream-dopamine link essentially supports Freud’s premise that dreams are connected with our desires. Even Freud’s staunchest critic, the eminent neuroscientist J. Allan Hobson, concedes that “the unfettered play of dopamine in REM sleep is in keeping with the assumption that dreaming is ‘motivated’ and that important motivational goals may be revealed in dreams.”
Does this then mean that Freud is right? Not necessarily. While the dream-dopamine pathway association is consistent with Freudian dream theory, there might nevertheless be alternative explanations for the role of this pathway. However, there is accumulating evidence that there may be merit to the claim that dreams may express the fulfilment of wishes.