Incredible as it seemed, the medical team concluded that sleepwalking was the one explanation that fit all the facts of the case. And indeed, as James Vlahos reports in the September 2012 issue of Scientific American, research over the past two decades since the Toronto tragedy supports the idea that the brain does not fall asleep all at once; and in some small number of individuals the timing with which various regions of the brain go offline becomes so disorganized that these people can walk, sleep, drive or cook entire meals without any awareness of what they are doing.
Why did Parks drive to his in-laws' home in his sleep rather than some other random address? Researchers believe that the part of his brain that wasn't asleep was just enacting what he had planned to do later that day. Why did Parks attack his in-laws so violently? Even the prosecution could not come up with a motive for the crime. Nor did it suggest that there was any advantage Parks might have gained because of it.
More than likely, sleep scientists think, Parks was not acting out a dream. The kind of sleepwalking he experienced occurs during a stage of sleep in which dreams are uncommon and consist mostly of fragmentary images. In addition, the part of the brain that tells us which actions are appropriate in a given situation (the prefrontal cortex), is inactive in this stage of sleep.
Instead, it appears that Dennis Woods found his son-in-law wandering about in the dark, tried to stop him and Parks responded as if his life were in danger. The part of his brain that could have told him otherwise was so exhausted by the previous night's insomnia and the stress of his gambling debts that it was, tragically, unavailable to inhibit his lethal actions.