The natural state of rest for human and animals is sleep. Regular sleep is essential for survival. There are two broad types of sleep; rapid eye movement and non-rapid eye movement. The stages of sleep were defined in 1937 by Alfred L. Loomis who determined five stages of sleep from A through E. This covered the full range from deep sleep to wakefulness. This definition has been refined through time and is now ranked as three distinct stages of non-rapid eye movement and one stage of rapid eye movement. In non-rapid eye movement sleep there is little dreaming; rapid eye movement sleep accounts for 20-25% of total sleep time in normal adults and accounts for memorable dreams.
Each stage of sleep has unique characteristics; each stage lasts in humans from 90 to 110 minutes on average and has distinct physiological characteristics. Failure to complete the sleep stages may lead to sleep deprivation and a feeling of tiredness upon waking.
Sleeping pills, alcohol and stress can contribute to disruptive sleep patterns and may increase the feeling of tiredness. The National Sleep Foundation (US) suggests that an adult requires seven to nine hours of sleep. Proper sleep benefits performance, memory, problem solving, health and reduces the possibility of accidents. Some Physicians have attributed some forms of sleep fatigue to sleeping environment such as noise levels, humidity and the particular mattress or bed being used.
There are many ongoing discussions about sleep in the blogosphere. Dr. Michael Breus, Ph.D. and owner of the Insomnia Blog, offers advice and up to date news in the world of sleep and insomnia.Powered by Sidelines