Sleep, Dreams and REM Sleep Behavior Disorder :: Biology Essays Research Papers

Sleep, Dreams and REM Sleep Behavior Disorder The discovery of rapid eye movement (REM) sleep suggested that sleep was not, as it was thought to be, a dormant state but rather a mentally dynamic one. Your brain is, in fact, very active in this state, almost to the level at which it is when a person is awake. Yet during this active stage in which most dreams occur, the movements of the rest of the body are completely stilled. To imagine this paralysis during dreams not occurring is a frightful image, since in many cases dreams are violent and active. When the neurotransmitters that control the movement of the body do not work properly the person develops REM sleep behavioral disorder (RBD). While we are sleeping the sensory world is essentially revolving around us without our knowledge. Our senses of hearing, touch, taste, sight, and smell no longer function as they do when we are awake. Except for the threshold for each of these senses that each of us has while we sleep, our inner systems are working essentially free of input from the outside world. And yet people are able to have vivid dreams. The cortex can only pass into sleep mode with the help of the are of the brain called the thalamus. The thalamus is one of the two structures that make up the diencephalon, the lower part of the fore brain. Its main function in mammals is as the relay station of sensory information its way to the cortical center. Specific regions of the thalamus, as well as different nuclei process different sensory information on its way to the cortex. In normal sleeping patterns a person usually passes through five phases of sleep, the fifth being REM. The sleeping human passes cyclically through these five phases throughout a night's rest. These phases can be defined in electrical activity of the brain; much like the activity of the heart is often defined. The technique of measuring the electrical activity of the brain is call Electro-encephalogram, or EEG. When the electrical events of a person's brain are graphed on a electrical magnitude versus time axis the graph of a person who is in different stages of being asleep or awake appear to have different levels of electrical activity occurring in the brain. (See (14)) During the cycle of the phases each lasts for a different period of time during the time we are sleeping.