Sleepwalking may have emerged as a defense mechanism
In 1987, Toronto's Canadian Kenneth Parks drove 23 kilometers and murdered his mother-in-law. Apparently he was in a sleepwalking state, a theory reinforced by the fact that he didn't remember the act and had an excellent relationship with his wife's mother. Already in 2008, an English teenager jumped from the eighth floor also while sleeping.
Sleepwalking is a condition that affects about 4% of adults, according to recent research. Most of the time, it is harmless. Some people even do amazing things in this state, such as the British artist Lee Hadwin, who produces his works while sleeping.
In recent years, the number of sleepwalkers has been increasing worldwide, mainly due to the unstoppable use of sleep-inducing drugs. But why does this happen? Why do some become dangerous while others awaken talent? Science tries to find out and already has some clues.
Archaic survival system
In these states, active areas were observed in brain regions involved with the emotional system (in the limbic system) and also in motor activity (within the cerebral cortex). This is very similar to when we are awake.
What really differentiates is that regions of the frontal cortex and hippocampus, which control rationality and memory, remain dormant. That is, it is as if only half of our brain wakes up, and we have no control over some actions. "The rational part is in a sleep state and does not exercise its normal control over the limbic system and the motor system, " explains Italian neuroscientist Lino Nobili.
Thus, it is as if our body activates a very archaic survival system, something that can be seen in escape situations or during a fight, for example. But why does the brain behave this way instead of waking up completely? The answer may lie in our ancestors.
Ready for action
Back in the past, when we were still living in nomadic tribes, we were at the mercy of different predators. Therefore, the time of sleep needed much more attention than today. Today, our rooms protect us, but the innate preservation instinct remains. However, when we sleep somewhere new for the first time, one hemisphere of our brain remains more active than the other, ready to respond to any potential danger.
These bursts of activity in areas related to the motor and limbic system can occur even when sleepwalking does not exist. “During sleep, we may have a motor system activation, so although you are sleeping and not moving, the motor cortex may be in the same state as you are, ready to act, ” says Nobili. “If something really goes wrong and endangers you, you don't need the rationality of your frontal lobe to escape. You just need a ready engine system, ”he adds.
The process of letting the body know when to wake up in case of danger does not seem to work very well in people who are sleepwalking constantly, but this is still an interesting feature of the evolution of our species.
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