The circadian rhythm, present in humans and most other animals, is generated by an internal clock that is synchronized to light and dark cycles and other cues in an organism’s environment. Learn about fatigue, sleep monitoring and recording, sleep patterns, sleep inertia, factors that influence quantity and quality of sleep, sleep disorders like sleep apnea, insomnia, and narcolepsy. We shall be exploring the chemical and biological changes (melatonin, your master clock, light disruption, and jet-lag) that occur when the circadian rhythms are not met, and how we go about improving well-being by meeting each sleep cycle.