The Science of Dreams

Humans have tried to explain our dreams for centuries. The Greeks believed they possessed prophetic powers, whilst early civilizations saw them as a window between our world and the realm of the gods. But why do we dream? Can you remember what you dreamt about last night while you were sleeping? How reliable is that memory, and what does it all mean?

Dreams are an impractical thing to study. Although they are a universal experience, they are inherently subjective and difficult to relay. Sigmund Freud put forward his book “The Interpretation of Dreams”, which sets out his theory of dreams as a representation of our unconscious desires and conflicts, giving us insight into our deeper selves. Freud went on to found the field of psychoanalysis with this work, however his approach is often seen as unscientific.

The invention of electroencephalograms (EEGs)  – a method of revealing patterns of electrical activity in the brain – by Hans Berger in 1924 led to the modern era of dream research. This gave scientists a way to study the dreaming brain and pinpoint when a sleeping person might be dreaming. Using methods such as sleep studies, fMRI, EEG and subjective “dream reports”, scientists have come up with many theories as to why we dream.

Antti Revonsuo, a Finnish neuroscientist, provided the ‘Threat Simulation Theory’ which suggests dreams serve the biological function of rehearsing threatening situations during sleep to aid survival. 

Allan Hobson, a Harvard psychiatrist who studied the dreaming brain for six decades, proposed the ‘Activation-Synthesis Model” which suggests dreams are our brains way of making sense of activity that occurs while we sleep. Circuits in the brainstem are activated during REM (rapid eye movement) sleep, which leads to areas of the limbic system involved in emotion, sensation and memory to become active. The brain synthesises and interprets this activity, attempting to create meaning from these random signals resulting in our dreams.

Other theories suggest dreams are a way of consolidating our memories or processing our emotions, with neuroimaging studies revealing significant activity in emotion-related brain regions during REM sleep.

Despite many decades of dream research, there is still no consensus on why we dream. According to Hobson, "Dreaming may be our most creative conscious state, one in which the chaotic, spontaneous recombination of cognitive elements produces novel configurations of information: new ideas".