August 17, 2010
Neurons, the signal centers of the body, act simply to create a complex system. A single neuron has dendrites, the cell body, and a long axon. They get, carry, then send signals in the form of a very low-level electrical impulse.
When you touch a hot cup of Gimme! Coffee, the heat radiates from the mug to the nerves in your fingers. The neurons use chemicals like sodium, potassium and calcium to open or close gates in the cell membranes. By controlling the amount of chemicals inside of the cell compared to outside, the neuron creates an electric signal. It sends that signal to the next neuron, to the next, to the next, until the brain gets the message “HOT!” and sends a signal back to advise your hands to let go of the coffee.
To visualize this process, think of watching dominoes topple at the Broome County Arena. It’s hockey season. On the ice, an ambitious intern has set up two domino-neuron models. On the left side of the arena, there are hundreds of possible places to push over a domino. These domino dendrites just need a light tap from the waiting Mike Brodeur’s hockey stick to set the cascade in motion.
This domino model converges to one large domino (the main body of the neuron). One solitary line of dominoes stretches from here to the blue line (the axon). At the blue line, Cody Bass waits, facing the opposing blue line. There sits another array of dominoes, set up in the same way – dendrites to the body to the axon. This second web of dominoes starts at the blue line and ends at the goal.
On the left, Brodeur topples any one of his dendrite dominoes. He might even start two or three if the impulse is strong. The dominoes topple until they get to the large domino. This domino falls over, and the message carries along the single line where Bass hovers. As soon as Bass sees the last domino fall, he skates over to the opposing blue line and topples dominoes on that mock neuron.
Now you have a slow-motion idea of how your brain works. Millions of these neurons in a chemical bath signal each other. On, off, off, on. Get excited, calm down. By taking a basic neuron and making millions upon millions of interconnections, we think, we breathe, we exist.
Doctors measure this signaling action to get an idea of what might be wrong with the brain, researchers use it to understand how the brain works. This leads us back to sleep.
Researchers in Pennsylvania wanted to know how effective one night of “catch-up” sleep would be for adults who had a week of inadequate sleep. During a normal work week, many people get less sleep than they need. On the weekend, these people take a day and sleep in. (This is very common for teens as well, but since this study focused on adults the results may or may not apply for that age group.)
A willing group of 159 healthy adults between the ages of 22 and 45 volunteered for the study. They started out rested, then for five days they were allowed to sleep for only four hours. On the sixth day they divided up into groups, and allowed to sleep from 0 hours to 10 hours to recover from the week of short sleep.
The researchers then looked at the participants’ brain waves after the recovery sleep session. As expected, the longer the adults were allowed to sleep, the more their brain recovered from the five nights of short sleep. But even for those who slept for 10 hours, they were not as alert or awake as they had been at the start of the study.
This sleep study had some very specific parameters – healthy adults, five days of sleeping from 4am to 8am, and up to 10 hours of recovery sleep, so the scientific conclusions are obviously limited. But as an individual, you can start to make some logical assumptions about your own sleep needs. For example, say you know that you really need 8 hours of sleep a night to feel well-rested the next day. You decide to work a double-shift for a week, to pick up some extra fun money, so you get only six hours of sleep every day for a week. Plan for some extra pillow-time on the weekend to enjoy that fun you’re working so hard to buy.
What’s the difference between heavy sleepers and light sleepers? A group of researches in Massachusetts wanted to pinpoint the reason. Again by looking at the brain waves our neurons create, researchers found something very interesting.
As sound enters the brain through the ear, the sound signal travels to a part of the brain that reacts to these sounds. Heavy sleepers generate lots of brain waves (called “sleep spindles”) that probably keeps the sound signal from reaching this reactive part of the brain. Since the brain effectively doesn’t “hear” what their ears have picked up, the heavy sleepers slumber on. Light sleepers don’t generate as many “sleep spindles”, so when their ears hear something the brain reacts to the sound and they wake up.
This has direct applications for plenty of people; people who sleep near noisy freeways, are trying to recover in a hospital, or in an apartment with paper-thin walls. By understanding this internal noise canceling process, innovators may be able to create devices or drugs to help light sleepers get a better night’s sleep. In the meantime, keeping the noise from getting to the ear may be the best solution for light sleepers with a good pair of earplugs.