The able-bodied dreams of people with a variety of disabilities challenge the theory that dreams are mere echoes of your day
"We had to flee. After a frantic race I started walking, carrying my daughter in my arms…" No matter how exciting to the dreamer, listening to people recount their dreams is notoriously dull. But reports such as this one, from someone who was born paralysed from the waist down, are perhaps more interesting.
This is because a flurry of recent dream studies in people with disabilities are challenging our understanding of why we dream. The results seem to suggest that dreams, besides being a surreal echo of our waking lives, have a reality of their own: they may even spring from innate, fully functional representations of our body and sensory perceptions that do not always match real-life situations.
The idea that dreams are linked to our waking reality - known as the continuity hypothesis - can be traced back to Sigmund Freud. The basic premise is that our dreams are determined by the thoughts, feelings and events that we have experienced during our waking hours, whether recently or further into the past.
While this hypothesis cannot account for everything - why we occasionally fly in our dreams, for example - it is the dominant idea, says dream researcher Martin Schredl at the Central Institute of Mental Health in Mannheim, Germany. He says there is a thematic continuity between waking and dreaming: “Dreams evoke specific emotions and reactions within the dreamer, and these are very closely related to actual waking-life issues.”
To explore whether dreams are indeed a one-way street from the outside in, Alan Hobson of Harvard Medical School in Boston and Ursula Voss at the University of Bonn in Germany, and colleagues, collected dream reports from four people born with paraplegia, 10 people who were born deaf and did not speak, and 36 able-bodied people acting as controls. The volunteers were asked to write down their dreams for two weeks, paying particular attention to the frequency and intensity of their movements and sensory experiences.
When the team analysed the dream reports, they were in for a surprise. About 80 per cent of the dream narratives of the deaf participants gave no indication of their impairment: many spoke in their dreams, while others could hear and understand spoken language. The dream reports of the people born paralysed revealed something similar: they often walked, ran or swam, none of which they had ever done in their waking lives (see “Whose dream is it anyway?”). Most importantly, there was no difference between the number of such bodily movements in the dream reports of the people with paraplegia and in those of the deaf and able-bodied subjects (Consciousness and Cognition, DOI: 10.1016/j.concog.2010.10.020).
In June, another group reported similar results. A team led by Marie-Thérèse Saurat of the Pitié-Salpêtrière Hospital in Paris, France, analysed the dreams of 15 people who were either born with paraplegia or acquired it as a result of a spinal-cord injury, and compared them with dreams of 15 able-bodied volunteers. Dream reports collected over six weeks showed that all but one person with paraplegia dreamed of being physically active and voluntarily moved their legs in their dreams. And people with paraplegia - even those born with the disability - dreamed of walking just as often as the healthy controls (Consciousness and Cognition, DOI: 10.1016/j.concog.2011.05.015).