Sleep | Aranee – 35th Batch
“We sleep one third of our life away”
Most of us believe that sleep is essential for physical and mental rest.But we are quite active mentally and physically in sleep. If sleep is meant only for rest, it coud be achieved by practising relaxation techniques and we don’t need to spend nearly one third of our lives sleeping. so there is something more about sleep is that it is a coordinated process occurs through distinct stages which is believed to be crucial to brain development and necessary to help consolidate the experiences in the wake stage.
Sleep is categorized into Rapid Eye Movement sleep (REM) and non-Rapid Eye Movement sleep (NREM) depending on the eye movements. NREM sleep is divided into four stages. In stage 1 and 2 a person undergoes light seep and could be easily awaken. The wave pattern in EEG resembles theta waves in stage 1 and alpha like spindles in stage 2. Here the EEG recordings show low amplitude and high frequency waves. But in later two stages the frequency lowers and the amplitude increases and thus here a person goes into deep sleep.
The next stage is REM. It was discovered in 1953 by Aserinsky and Kleitman. They found that it was characterized by periodic recurrence of rapid eye movements inked to dramatic reduction in the amplitude of EEG which closely resembled stage 1 of NREM sleep. But here the muscle tone is reduced and the body is almost paralyzed. Thus it’s also known as paradoxical sleep where EEG resembled alert waking whereas behaviorally the person remains unresponsive and deep asleep. However, sleep is not interupted; indeed the threshhold for arousal by sensory stimuli and stimulation of the reticular formation is elevated.
Another typical feature of REM sleep is the occurrence of dreams. In the REM the brain stem which generate REM sends bursts of stimulations randomly to other parts of the brain. These stimuations are important for the maintenance of connections between the neurons and to the development of more synapses. Thus its important for intense learning and witch probably the reason why the children have more REM sleep than adults. It is believed that these stimulations are the reason behind dreams. Dreams are the attempts to fulfill peremptory wishes arising during sleep.
In a typical sleep, a person pass through stage 1 and 2 and spends about 100 minutes in stage 3 and 4 then the REM follows and the cycle is repeated in 90 minutes interval. About three times each night we cycle through these stages
As sleep is not a dormant process and as it involves various coordinated brain activity, it is essential to get optimum sleep in accordance to the age and body physiology. Sleep is needed to recover all the work done when we were awake. Release of growth hormone in children and young adults increases during NREM sleep. This helps in the tissue repair including skin damaged by UV rays. During REM sleep the parts of the brain which was active in the day time is repeatedly stimulated. This helps in the learning process and to improve the memory. A good sleep helps to cope up with stress and can even improve our decision making as the brain integrates information it took during the day in REM sleep. Sleep deprivation can lead to lack of concentration and behavioral changes like aggression and irritability. A long term sleep deprivation can bring out medical and psychosocial issues. People not having proper sleep for a long time have an increased risk of cardio vascular diseases and diabetes mellitus in their later ages. Children with disturbed sleep are more likely to misbehave.
It is recommended that about six to eight hours of sleep is needed for an adult and about 10 hours for children. So optimum undisturbed sleep becomes an important thing to lead a healthy life.
B. Aranee – 35th Batch
This article by Ms. B. Aranee (35th Batch), appeared in the MSU Magazine - "Naadi - 12" published in December 2014