Dreams Studies show that in dreams things are seen and heard rather than thought. In terms of the senses, visual experience is present in almost all dreams auditory experience in 40 to 50 percent and touch, taste, smell, and pain in a relatively small percentage. A considerable amount of emotion is commonly present, usually a pure and single emotion such as fear, anger, or joy Two clearly distinguishable states of sleep exist. The first state, called NREM-sleep (non-rapid-eye-movement sleep), occupies most of the sleep period and is associated with a relatively low pulse and blood pressure, and few or no reports of dreaming. The second type of sleep, known as REM-sleep (rapid-eye-movement sleep) occurs cyclically during the sleep period with rapid eye movements and frequent dream reports. Typically, a person has four or five periods of REM-sleep during the night, whether the dreams are remembered often, rarely, or not at all they occur at intervals of about 90 minutes and altogether make up about 25 percent of the night's sleep (as much as 50 percent in a newborn child). Evidence indicates that a dream period usually lasts from 5 to 20 minutes. Sounds and touches working on a dreamer can go into a dream if they occur during a REM-period. Although mental activity may be reported during NREM-sleep, these are usually short pieces of thoughtlike experiences. Modern dream research has focused on two general interpretations of dream content. In one view, dreams have no meaning of their own but are simply a process by which the brain integrates new information into memories. In the other view, dreams contain real meaning symbolized in a picture language distinct from conscious logical thought. If dreams express important wishes, fears, concerns, and worries of the dreamer, the study and analysis of dreams can help reveal previously unknown aspects of a person's mental functioning. There axe in general two opinions about what we experience in a dream: