“Dreaming allows us to safely be insane every night in our lives”
- William Dement
It is amazing to think that 33% of our lives we spend sleeping. Despite this fact, we know little about sleep and we tend to disregard how important it is. You must sometimes ask yourselves: If our body and mind wants us to sleep for such long periods, don’t you think it is important part of our lives? We neglect sleep more than any other bodily function. Yet it takes most of our precious time. Think of our past when humans were hunters and barely had a safe shelter. There were hundreds of predators out there wanting to taste us for dinner. Staying asleep 8-10 hours a day would make us very vulnerable to those predators yet we managed to sleep. Why it is that sleep is so important?
Unfortunately, we are not at the point where we can actually answer all those questions. Advances in science, although groundbreaking, have not figured it out completely. Based on some recent studies we have a good idea why we need to sleep for so long.
Sleep 101
The human sleep cycle can be divided into 5 stages: stages 1 through 4, and REM (Rapid Eye Movement). Stage 1 is our lightest sleep phase. It is when we are falling asleep and we drift from sleep to wake stages. In this stage, it is very easy to be awakened and we often experience involuntary muscle contractions.
During stage 2 our muscle activity and our brain activity slows down with some bursts of rapid waves called sleep spindles. During stages 3 and 4, our bodies are inactive and we experience extremely slow brain waves called delta. Stage 3 and 4 are the stages of very deep sleep. This is the stage were we do not hear our alarm clocks and it is when people sleepwalk or kids have night terrors. If you are awakened at this stage, you will fill disoriented and will typically not remember what happened for a few minutes. Our fifth stage, REM, is the last stage of the cycle and is characterized by rapid breathing, eye jerking, increased heart rate, male erection and limbs become temporarily paralyzed. When someone is awakened from this stage we tend to describe bizarre stories: Dreams. The whole cycle takes about 90-110 minutes, which means that we typically go through 3-5 cycles per night. We tend stay in stages 3 and 4 about 20% of a whole sleep cycle. REM stage gets longer as we go through cycles lasting more towards the end stages of sleep.
Our sleep-wake cycle is controlled mainly by a milieu of chemicals called neurotransmitters. They do this by acting as signals to a select group of neurons in our brains. Some of these neurotransmitters include serotonin, dopamine, GABA and norepinephrine. These chemicals turn on and off groups of neurons that control the wake-sleep cycle. There are other chemicals other than neurotransmitters involved in the sleep cycle as well. For instance, Adenosine (a purine nucleoside) has been shown to have increased levels in our blood stream causing drowsiness. Adenosine is then broken down while we sleep.
by Dr. German Garcia-Fresco
Neuroscientist
Perreault Magazine - 56 -
SLEEP TO SUCCESS