Abstract: The human brain is the most complex organ in the body. Its functions control every aspect of life. It is important to try to understand how the brain works and learn the effects of natural and unnatural substances on it. To observe chemical effects on the brain, you must first understand the chemicals and how the brain works to interpret and react to the signals sent by these chemicals, rhythmically and physiologically. Several chemicals observed include: cocaine (and other chemicals), seratonin, and melatonin. Nature and life are full of rhythms. Rhythms in nature include: day and night, seasons, tides, and lunar and solar cycles. Humans are driven by rhythms such as: heartbeats, breathing rate, sleep patterns, and brain rhythms that include chemical and hormonal secretion. Without rhythms, life would be uncontrollable and chaotic. We know relatively very little about that complex organ called the brain. Our brain responds to the external eternal rhythms of nature such as the seasons, tides, sun and moon. Animal survival instincts are based on the rhythms and drives of the brain. The brain is a collection of tissues that perform and respond to basic functions, desires, and needs. The human brain is the most modified, enriched and complex brain in evolutionary terms, yet, in its most basic form, it is the same as other brains in the Animal Kingdom. If you eliminate the cerebral cortex, you essentially eliminate humanity and the brain becomes identical to that of a cat. If you remove even more, the brain becomes like that of an iguana. However, the human brain is not so simple, which makes it even more sensitive and fragile to external forces... middle of paper... Information Processing: The Nervous System." Biology: Life on Earth. 3rd ed. New York: Macmillan Publishing Company, 1993. 776-805.The Brain [videotape]. Prod. Enciclopedia Britannica Educational Corporation. Open University in association with Penn State, Division of Media and Learning Resources, ca. 1993 Springer, Peter Katel and Binnie K. Fisher "Melatonin Mania", November 6, 1995: 60-63.http://www.anarch.ie.utoronto.ca/courses/ind321/lectures/perception/waves.htmlhttp:/ /www.ceri.com/melatonin.htmhttp://www.cityscape.co.uk/users/ad88/mel.htmhttp://www.lifeplusvitami ns.com/somniset.htmlhttp://www.medaccess.com/ physical/drugs/datb_06.htmhttp://www.members.gnn.com/natbasics/index.htmhttp://www.stanfordsw.com/wave.htmhttp://www.vitawise.com/melatoni.htm