THE NIGHT TRAIN CONDUCTOR’S RULES
“We welcome you on board and wish you a pleasant night’s sleep.” The crackly voice of the night train conductor creeping out the speaker system lingers in the 6-seater compartment. Five travelers, one seat to spear and no room for a stretched leg or an arm anywhere. We look at each other and burst into nervous laughter.
I dread this kind of travel. But to get to some places, a flight takes just about as long. And if traveling by night, at least your day can be saved for exploration!
The compartment empties one by one miraculously and I have 6 seats that fold down all to myself – for about 4 hours of my 12 hour trip. I feel lucky and spread out on this king size surface, a moon-scape with seat rests and edges here and there. My sleep is short and restless, even though the moving train soothes like a mother rocking her child.
Sleep is beautiful
At 4:15 am I need to change trains (in a city that shall remain unnamed). I have to spend 2 hours before continuing my journey. Walking around the train station, speckled with occasional late-night wanderers, I locate the waiting room where a few more travelers are sitting or laying down, as comfortably as one can. A handful of seats are available, even another double seat. There, I make myself a makeshift night rest, or at least one for the next two hours.
A light sleep takes me to strange dreams for a while. A loud, rude “Sit up, sit up.” jerks me back to the forsaken place of a train station during the twilight hours. The security guard is making his rounds, waking up anybody that is laying down to sleep.
I sit up, dazed from the rude awakening. I try to sleep sitting up but that just won’t work and now I’m indignant, having been woken up so rudely!
It’s now about 4:30 am. The security guard is pacing again and I approach him to inquire why I am not allowed to sleep in the waiting room. His answer, “It’s a waiting room, not sleeping room.” does not satisfy me. I inquire again, “Why may I not sleep in the waiting room when I have to wait for a connection between 4 am and 6 am?” “Those are the house rules.” he says.
When moisture refreshes the mind
Even more enraged, I leave the train station to walk it off for the next hour. Some fresh air always calms.
Sleep is beautiful and when an outside force ceases it, I feel powerless.
But more often than not, my very own choices lead to lack of sleep!
It is important, we all know and feel it. But what exactly happens when we sleep? And how does this phase of rest reset us for another day of exploration and discovery?
Galen of Pergamum (129–216 CE), the prominent ancient Greek medical researcher, surgeon, physician and philosopher had some thoughts on this matter about 2000 years ago. He imagined, influenced by Hippocrates’ theory of humorism (also known as the four humors – black bile, yellow bile, blood, and phlegm), that during waking hours the brain’s motive forces, a juice if you will, would leave the brain, flow into other parts of the body and animate them. Only during sleep would the moisture return to the brain to refresh the mind.
It’s fascinating that Galen’s cleansing effect theory of a good night’s sleep, it turns out, is not as far fetched as it may seem at first.
The plumbing network in the brain
The neuroscientist, Jeffrey Iliff, exploring brain functions, explains that all cells must continuously be fueled with nutrients and oxygen through a complex network of blood vessels. For the brain, an organ that uses a quarter of the entire body’s energy supply with only 2 percent of its mass, this is essential. Consuming nutrients means producing waste. The lymphatic system is a parallel network of vessels taking up protein and other refuse from the spaces between the cells and discarding them through the blood.
The brain has no lymphatic system. Jeffrey Iliff and his team found that the cerebrospinal fluid, a clean, clear fluid, fills the space surrounding the brain. This fluid takes up the waste from the brain and expels it into the blood through a specialized plumbing network. (Part of the waste being transported out, is the protein amyloid-beta, that has been liked to the Alzheimer’s disease. But many other health risks have also been linked to poor or lack of sleep).
The cerebrospinal fluid on the outside is pumped into and through the brain along the outside of the blood vessels, clearing waste from between the spaces of the brain cells, reaching the entire brain’s volume. Jeffrey Iliff sees this as a sort of repurposing of the veins to act like the lymphatic system in a space where there is no capacity for another set of vessels.
So far so good. But the most surprising discovery of this study may just be this: the rushing of fluid through the brain only happens during sleep. Then, the brain cells shrink to open up spaces for the cleansing effect of the cerebrospinal fluid to flush through. Ingeniously, while the brain is most active, it holds off the clearing of accumulated waste.
Now Galen’s visual analogy of fluid leaving the brain and returning to revive it doesn’t seems so farfetched after all…
It becomes clear as day, a good night’s sleep allows the cleaning up of the never-resting brain. And so ensures a healthy mind and body.
The brain-wide pathway
For a detailed video for the waste clearance process, please have a look at the TED presentation video from September 2014 by Jeffrey Iliff. He is also the author of “Brain-wide pathway for waste clearance captured by contrast-enhanced MRI”, published in The Journal of Clinical Investigation on March 1, 2013.
Written by Elisabeth Stephan
XuendR’s Art Director
… and a keen discoverer of self-perception