Sleep is one of the most vital components of all life functions. When sleep is positive in terms of both quality and quantity, it provides the necessary energy and alertness to perform daily tasks.
Just as important, sleep impacts the immune systems, memory functions, outward appearances and performance levels of all humans. In short, most aspects of life are largely dependent upon sleep.
Experts recommend that persons of specific age groups receive a corresponding amount of sleep. Teenagers, for example, need between 8.5 and 9.25 hours of sleep every night. Adults require from 7 to 9 hours of sleep. This is likely to vary with age, illness and work demands.
When sleep falls short, however, the body does not have time to complete all of the phases necessary for memory consolidation, muscle repair and the release of hormones that regulate appetite and growth. The consequence is waking to feel less able to meet the demands of day-to-day engagements.
The Inner Workings of Sleep
Contrary to popular thought, sleep is not a continuous event in which the body simply lies motionless. In truth, sleep follows an alternating pattern of NREM (non-rapid eye movement) and REM (rapid eye movement) throughout the entire time. Each interval repeats itself approximately every 90 minutes. This is the underlying biology of sleep, whereby specific events occur to repair both the mind and body.
NREM accounts for approximately 75 percent of the time that is spent sleeping each night. As a person begins to fall asleep, he or she first enters NREM. It is composed of four stages and occurs as follows:
- Stage 1: early moments between being and awake and falling asleep. Light sleep soon ensues.
- Stage 2: onset of sleep occurs and a person becomes disengaged from his or her surroundings. Breathing and heart rate both regulate and the body temperature begins to drop.
- Stages 3 and 4: deepest and most restorative periods of sleep. Many events occur during these stages, whereby the blood pressure drops, breathing becomes slower and muscles relax. In terms of health, blood supply to muscles increases, tissues grow and repair, energy is restored throughout the body and hormones are released, including those for growth, repair and muscle development.
REM occurs the rest of the 25 percent of time in sleep and is characterized by the eyes darting back and forth. It first takes place approximately 90 minutes after a person falls asleep and then accounts for the period from which persons wake. This stage is responsible for the following health functions:
- Feeds energy to the brain and body
- Supports daytime performance
- Body becomes completely immobile and relaxed as muscles are turned off
- High brain activity occurs and dreams take place
Sleep and the Brain
In the past, health officials believed sleep was a passive state. Today, it is now known as a dynamic process in which the brain remains active. For example, each stage of sleep as depicted above is marked by a different corresponding brain wave. During stage two of NREM sleep, brain waves begin to slow with occasions bursts of rapidity. In stage three, extremely slow brain waves known as delta waves begin to form. They are interrupted by smaller and faster waves. In stage four, delta waves are the primary form of brain activity.
During REM, the brain is highly active, and overall brain metabolism may be increased by as much as 20 percent. This period of sleep represents electrical brain activity that is similar to what occurs during wakefulness. Physically, the heart rate and breathing both become rapid and irregular during REM. Blood pressure also increases.
Among the most prominent health functions of sleep are increased cell production, restoration to the nervous system and resting of brain parts that control emotions and social interaction. Some tips to improve sleep and thus enjoy its health benefits are as follows:
- Sleep in a well-ventilated room with fresh air
- Avoid exercise at least three hours before sleep
- Avoid alcohol, caffeine and sugar at least four hours prior to sleep
- Establish a routine of going to sleep and waking at the same time every day
- ^ Sleep Science: Promoting Health and Healing (www.hellolife.net)
- ^ http://www.sleepfoundation.org/category/article-type/how-sleep-works (www.sleepfoundation.org)
- ^ http://www.emedicinehealth.com/sleep_understanding_the_basics/page5_em.htm (www.emedicinehealth.com)
- ^ http://health.howstuffworks.com/mental-health/sleep/basics/sleep.htm (health.howstuffworks.com)