ISLAMABAD: We tend to think of being asleep or awake as an either-or prospect: If you’re not asleep, then you must be awake. But sleep disorder specialist and neurologist Guy Leschziner says it’s not that simple.
“If one looks at the brain during sleep, we now know that actually sleep is not a static state,” Leschziner says. “There are a number of different brain states that occur while we sleep.”
As head of the sleep disorders center at Guy’s Hospital in London, Leschziner has treated patients with a host of nocturnal problems, including insomnia, night terrors, narcolepsy, sleep walking, sleep eating and sexsomnia, a condition in which a person pursues sexual acts while asleep. He writes about his experiences in his book The Nocturnal Brain.
Leschziner notes that the different parts of the brain aren’t always in the same stage of sleep at the same time. When this happens, an individual might order a pizza or go out for a drive — while technically still being fast asleep.”Sometimes these conditions sound very funny,” Leschziner says. “But on other occasions they can be really life changing, resulting in major injury or, as one of the cases that I described in the book, in a criminal conviction.”
We used to think that people don’t really remember anything that occurs in this stage. That seems to relate to the fact that the brain in parts is in very deep sleep whilst in other parts is awake. What we have learned over the last few years is that actually quite a lot of people have some sort of limited recall. They don’t necessarily remember the details of all the events or indeed the entirety of the event, but sometimes they do experience little snippets. … On one occasion, [a patient] dragged his girlfriend out of bed in the middle of the night because he thought that a tsunami was about to wash them away, and those kinds of events with strong emotional context are often better remembered.
On how sleepwalking demonstrates the brain can be in multiple sleep stages at once Certain parts of the brain can remain in very deep sleep … [such as] the frontal lobes, which are the seats of our rational thinking or planning or restricting on normal behaviors, whereas other parts of the brain can exhibit electrical activity that is really akin to being wide awake.
And it’s this dissociation, this disconnect between the different parts of the brain in terms of the sleep stages, that actually give rise to these sorts of behaviors.
On what causes sleepwalking
We know that sleepwalking and these related conditions seem to run very strongly in families. So there seems to be some sort of genetic predisposition to being able to enter into this disconnected brain state, and we know that anything that disrupts your sleep if you have that genetic predisposition can give rise to these behaviors. So, for example, I’ve seen people who have had non-REM parasomnia events [such as sleepwalking] triggered by the fact that they sleep in a creaky bed and their bed partner rolled over [or] sometimes a large truck [drove] past in the street outside the bedroom.