Jean Scott of Palmerston North asks :-

M Pollard, of Palmerston North, asked:-

How do people who have been blind from birth dream?

David Bilkey, a psychologist at Otago University, responded.

Most people, whether we are sighted or blind, have several periods of "dream-sleep" every night. We know this because sleep researchers have discovered a regular cycle of brain activity that occurs around five times over a normal eight hour sleep. Within each cycle there will be a period during which our brain activity changes to look very much like it does when we are alert and awake. If people are woken up during this stage of sleep it is highly likely that they will report being in the middle of a dream. The discovery of this link between brain activity and dreams was a milestone for sleep researchers as it meant that people could be woken during this "active-sleep" stage and asked about their dream content.

As you might expect, we know that most dreams of sighted people have a strong visual component. In fact, this visual component is so strong that it may be difficult to imagine how it is possible to dream without these images. Somewhat surprisingly, however, it has been shown that people who have been blind from birth dream just as much as, and have dreams that in both general form and content are very similar to, those of sighted people. The only difference is that their dreams do not have a visual component and may have a greater emphasis on touch and hearing. Importantly, these dreams have features that one might expect to be dependent on vision, such as a sense of movement and a sense of space. Dream experiences reflect, therefore, the experiences that individuals have while they are awake, whether those individuals are sighted or not. To quote a scientific paper on this topic that nicely sums up this idea: "dreams never are simulations of seeing; they are simulations of living" (Kerr and colleagues, 1982).