Sleep is a behavior seen in almost all animals. We spend around one third of our life time asleep. Prolonged sleep deprivation can lead to severe mental and physical problems and result in death. Lack of proper sleep can lead to reduced immunity, impairment in memory, reduced alertness and clarity if thinking. Disturbances of sleep are commonly found in majority of psychiatric disorders.
Generally people think of sleep as a uniform state. But studies using electrophysiological equipments have shown that sleep can be divided into distinct stages which occur in a predictable sequence. This pattern is referred to as sleep architecture.
Sleep can be defined as a state of rest with reduced awareness about the environment that is easily reversible. Thus it is different from other superficially similar states like coma.
Human sleep is subdivided into 2 types based on certain electrophysiological parameters and other phenomena. These are the REM (rapid eye movement) and Non REM sleep. REM sleep gets this name as there are rapid movements of the eye balls during this phase. This phase is associated with vivid dreams.
As one falls asleep the first stage occurring is called Stage I of NREM sleep. Then we successively pass through stages II, III and IV. Each stage has characteristic features on the Electro encephalogram (EEG). Slowing of EEG activity is noted from stages I through IV. Stages III and IV are together called Slow wave sleep (SWS) because the EEG record show considerable slowing during these stages. The EEG of REM sleep shows fast activity resembling the waking record.
REM sleep appears in bursts. At the end of approximately 90 to 110 minutes the first burst occurs. By this time the subject would have progressed to the SWS stages.
Subsequently, the subject moves back to SWS in around 20 minutes. Thereafter the sleep alternates between SWS and REM bouts every 60 to 90 minutes. The person enters the stages I and II of NREM only if wakes up again. Otherwise the rest of night is spent in SWS and REM sleep only.
Sleep is essential for growth and repair of the body, consolidation of memory and many other unknown functions. The secretion of growth hormone is maximal during sleep in babies, showing the important role of sleep in their growth.
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2 weeks ago
3 comments:
Dear Harish,
Why 'some' students experience uncontrolable sleep during 'some'classes?
What is the usual advice you give to such students?
Thank you
Anything boring or monotonous can induce sleep. Remember travelling in the same familiar route alone in a bus. You will surely feel sleepy. Feeling sleepy in class can be due to the monotony of the class or due to lack if interest in the subject. A full stomach reduces blood flow to the brain. This contributes to sleepiness after heavy food. Make some enquiries regarding his nocturnal sleep and sleep habits. If he is not getting the required amount of sleep at night, spill over of sleep can occur during the daytime.
For a student who sleeps only in some (few) class, we have to first find out if it is because the subject or teacher is really boring. This can be done easily. The student can eat lighter meals before the clases, take tea or strong coffee, both of which can retard sleep. He can try to develop some interest in the subject by making some reading beforehand. If there is a tendency to fall asleep in an irrestible manner,or if he sleeps in most classes, conditions like narcolepsy have to be ruled out.
we are always told as children, as an example almost worthy of emulation, that some great man or the other slept only 4 hours a day. Sometimes as children we wonder why we should be clipped over the ears because somebody slept only for 4 hours. We wonder how we are responsible for that fellow's insomnia. But nowadays parents are more knowledgeable. Does seeing a lot of dreams lead to less refreshing sleep ?
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