Contemporary culture increasingly suffers from problems of attention, over-stimulation, and stress, and a variety of personal and social discontents generated by deceptive body images. This book argues that improved body consciousness can relieve these problems and enhance one's knowledge, performance, and pleasure.
In the R&K standard, NREM sleep was divided into four stages, with slow-wave sleep comprising stages 3 and 4. In stage 3, delta waves made up less than 50% of the total wave patterns, while they made up more than 50% in stage 4. Furthermore, REM sleep was sometimes referred to as stage 5. In 2004, the AASM commissioned the AASM Visual Scoring Task Force to review the R&K scoring system.
Loomis provided the earliest detailed description of various stages of sleep in the mid-1930s, and in the early 1950s, Aserinsky and Kleitman identified rapid eye movement (REM) sleep. Sleep is generally divided into 2 broad types: nonrapid eye movement (NREM) sleep and REM sleep. Based on EEG changes, NREM is divided further into 4 stages (stage I, stage II, stage III, stage IV). NREM and REM occur in alternating cycles, each lasting approximately 90-100 minutes, with a total of 4-6 cycles.