Does anybody ever come home from a long day of work or a hard day at school and only one thing is on your mind. It is probably the greatest feeling on earth, well at least one of the greatest feelings on earth. What am I talking about? I am talking about sleep. Since the beginning of time history is filled with people fascinated with sleep. Does anybody ever think about why we sleep or what goes on to our brains while we sleep? Well before the twentieth century sleep was thought of as just a period of restful inactivity because there was no clear way to study brain activity.
But since then the invention of the electroencephalograph by German psychiatrist Hans Berger in the 1920s it gave sleep researchers a tool for studying brain activity.
These brain activities that they study are called brain waves. Today’s scientist research a number of physical functions during sleep such as eye movements, muscle movements, breathing rate, air flow, pulse, blood pressure, amount of exhaled carbon dioxide, body temperature, and breathing sounds.
There are two basic types of sleep. REM sleep also known as rapid eye movement sleep or active sleep, and NREM sleep, or non rapid eye movement sleep, also known as quiet sleep witch is divided into four stages witch I will describe shortly. I will also describe the changes in sleep over our lifespan. While you are preparing for bed you are up and reasonably alert so your brain produces small, fast brain waves called beta brain waves.
When your head hits the pillow your muscles begin to relax and your brains electrical activity starts to slow down making the brain produce slower and larger brain waves called alpha brain waves. During this stage you may start to experience odd but realistic sensations such as your name being called or you feel a falling sensation or maybe you see kaleidoscope-like patterns. These experiences are called hypnagogic hallucinations.