In about the 1950s, most people thought of sleep as a passive, inactive part of our daily lives. Now we know that our brains are very active when were asleep. Sleep affects us in many ways, that we are just beginning to understand. For instance, it affects how we function from day to day, it also affects our physical and mental health. In these next few paragraphs, I will talk about how much sleep we need, and what happens to our brain when we sleep.
The amount of sleep someone gets depends on many factors, take age for example. Infants need about 16 hours a day, while teenagers usually need at least 9 hours of sleep. Many adults sleep about 7 to 8 hours on average. However, some people may need as few as 5 hours or as many as 11 hours of sleep a day. Another thing that may affect the amount someone sleeps in a day is women in their first 3 months of pregnancy, they might need several hours of sleep. Some people may have sleeping problems such as insomnia, or deep sleep stages. Medication can also make a difference in how you sleep. When someone gets to little sleep, your body may get tired or sore and you will feel drowsy and tired. Many studies show that sleep deprivation is dangerous. Sleep-deprived people who are tested (by using a driving stimulator or hand-eye coordination) perform as badly or may even worse than those who are intoxicated.
Nerve-signaling chemicals called neurotransmitters control weather we are asleep or awake by acting on different groups of nerve cells in the brain. Nerve cells in the brainstem produce neurotransmitters such as serotonin and norepinephrine. They keep some parts of the brian active when you are awake. Other neurons at the base of the brain, signal when we fall asleep. Research also suggest that a chemical called adenosine builds up in our blood when we are awake and cause drowsiness. This chemical breaks down when we are asleep. Foods and medicine can change the balance of these signals. Caffeinated drinks or drugs such as diet pills stimulate some parts of the brain and can cause insomnia or an inability to sleep. People who smoke cigarettes, may often sleep very lightly and reduce the amount of sleep.
During sleep, we pass through five phases or sleep. During stage one, (which is light sleep) we drift in and out of sleep and can be awakened very easily. Our eyes move very slowly and our muscle activity slows. When a person is awakened from this stage, they often remember fragmented visual images. They may also experience sudden muscle contractions called hypnic myoclonia, which is often preceded by a sensation of starting to fall. These sudden movements are similar to the jump we get when we are startled. People awakened after sleeping a few minutes are usually usually unable to remember the last few minutes before they fell asleep. Researchers believe that it is related to amnesia (a disorder that causes you to forget simple things).
This explains why a lot of people don’t remember turning off ringing alarms in the morning. In stage two, our eye movements stop and our brain waves become slower. Stage three, our brain waves are extremely slow, and cause delta waves. By stage four, the brains delta waves increase and there is no eye movements or muscle activity. It may be very difficult to wake someone when they are in stages three and four. Those stages together are usually called deep sleep. People awakened during deep sleep do not adjust immediately and feel disoriented for several minutes before they wake up. The fifth stage is referred to as REM (rapid eye movement). When we switched to REM sleep, our breathing becomes more rapid, shallow and irregular, our eyes jerk rapidly in different directions and our limb muscles become temporarily paralyzed. Our heart rate increases and our blood pressure rises. When people wake from REM sleep, they often describe illogical and sometimes bizarre tales referred to as dreams.
REM sleep begins with signals from the area at the base of the brain called the pons. These signals travel to a brain region called the thalamus, which then relays them to the cerebral cortex-the outer layer of the brain that is responsible for learning, thinking and organizing information. The pons also sends signals that shut off the neurons in the spinal cord, causing temporary paralysis to the limb muscles. If something interferes with the paralysis, people will become to “act out their dreams physically. This is a rare and sometimes dangerous problem called REM sleep behavior disorder. For example, if someone was dreaming about baseball, they might run in to furniture or strike someone sleeping near by trying to hit a ball in a dream.
These stages progress in a cycle from stage one to the REM stage, then starts over again with stage one. We spend about 50% of our total sleep time in stage two, about 20% in the REM stage, and 30% in the other stages. Infants spend about half of their sleeping time in REM sleep. We typically spend more that two hours each night dreaming, so in one year you spend 720 hours dreaming.
Each year, at least 40 million people in America suffer from chronic, long-term sleeping disorders, and an additional 20 million experience occasional sleeping problems. These account for an estimated $16 billion dollars in medical costs each year. Doctors have come up with more than 70 sleep disorders, most can be managed effectively once they are correctly diagnosed. The most common sleeping disorders are insomnia, sleep apnera, restless legs syndrome and narcolepsy.
Almost everyone occasionally suffers from short-term insomnia. Insomnia almost always affects ones job performance and well being the next day. About 60 million Americans a year have insomnia weather it’s frequently or for extended periods of time. Insomnia tends to increase with age. Sleeping pills are usually prescribed for short-term insomnia.
An estimated 18 million Americans have sleep apnea. Sleep apnea is a disorder of breathing during sleep. It can occur with fat buildup or loss of muscle tone. These changes cause the windpipe to collapse during breathing when muscles relax during sleep. Sleep apnea is usually associated with loud snoring (not everyone who snores his this disorder).
As many as 12 million Americans suffer from RLS (Restless Legs Syndrome). RLS is a disorder causing unpleasant prickling, crawling or tingling sensations in the legs or feet and people tend to move them for relief.
Narcolepsy affects an estimated 250 million Americans. People with narcolepsy have frequent “sleep attacks” at random times of the day weather they have had a normal amount of sleep or not. The attacks can last a few seconds or as long as 30 minutes.
In conclusion, everyone needs sleep weather it’s 6 hours or 10 hours. Sleep helps us think more clearly, concentrate and provides us with enough energy to have an effective day.
