Sleep is composed of a sequence of successive sleep cycles that contribute to a healthy regenerative process for your mind and body. A complete sleep cycle consists of an REM (rapid eye movement) stage and three non-REM stages (labeled stages 1 thru 3). Each of these four stages is associated with different levels of arousal, unique brain wave activity, typical changes in heart rate and blood pressure, and varying quantities and patterns of movement. A medical sleep study, or polysomnography, measures all of these characteristics in a laboratory environment, to evaluate a patient’s sleep.
While there is no true substitute for polysomnography to obtain a complete medical evaluation of sleep, a strong correlation exists between the body’s movement patterns and its stages of sleep. Stage 3 non-REM sleep (also referred to as slow wave sleep, or deep sleep, in the medical literature) and REM sleep are both characterized by especially low levels of movement, e.g. in REM sleep your arms and legs are essentially paralyzed. These two stages are the periods when most dreams occur, and they are believed to play an especially important role in the rejuvenative process of sleep.
Utilizing the same three-dimensional accelerometry based technology that Shine uses to monitor your physical activity during the day, Shine tracks and analyzes your body’s movements at night. Shine uses proprietary algorithms to identify what we believe to be the most restful periods and labels them as deep sleep. These features are intended to help you learn more about your sleep and track your sleep habits and experience as they relate to your overall well-being. At this time, the deep sleep metric is not intended to describe medically defined periods within the sleep cycle. We are continuing to refine our sleep tracking features with increasing data and research, and we will keep you updated with new developments.
For more info on sleep, see http://en.wikipedia.org/wiki/sleep
-The Misfit Science Team