brain, spinal cord, and nerve disorders
Overview of Sleep
Introduction
Sleep is necessary for survival and good health, but why sleep is needed and exactly how it benefits people are not fully understood. One of sleep's benefits is its restorative effect on people's ability to function normally during the daytime. Individual requirements for sleep vary widely, usually from 6 to 10 hours every day. Most people sleep at night. However, many people must sleep during the day to accommodate work schedules—a situation that can lead to sleep disorders. No one knows exactly why people need to sleep. How long people sleep and how rested they feel after waking can be influenced by many factors, including the following: Level of excitement or emotional distress Age Diet Use of drugs For example, some drugs make people sleepy, and others make sleeping difficult. Some food components or additives, such ascaffeine, strong spices, and monosodium glutamate (MSG), may disturb sleep. Older people tend to fall asleep earlier, to awaken earlier, and to be less tolerant of changes in sleep habits. Snoring may interfere with sleep—the snorer's or the snorer's bed partner's. 