The sleep mechanics


By Hiya Islam


scienceSleep is heavenly. Nothing beats a great nap. Who said there’s plenty of time to sleep when we die? That’s garbage. There could never be a better feeling than waking up and feeling every inch of the body swell with energy and every bit of weariness flee to who knows where. Still, there is more to sleep than just closing the eyes.

As we sleep, our sleep progresses back and forth through a number of stages. Sleep alternates between NREM (non-rapid eye movement) and REM (rapid eye movement) phase. Sleep experts have used EEG (electroencephalogram) to study brain activity by monitoring changes in electrical activity during sleep. NREM makes up most of the night’s sleep and comprises of three stages. The first stage of NREM is what we call the light sleep. The individual is sort of alert of his surroundings and can be woken up with little effort. This lasts typically 5-10 minutes. The second stage lasting another 10-25 minutes prepares the body to enter the deep sleep mode. The breathing and heart rates slow down. The body temperature drops. And the brain activity decreases. A perfect power nap must last until this stage as the third stage is where the person sleeps deeply. Waking someone up at this point will leave the person groggy and grumpy. The stages then occur in reverse successively until REM phase. In REM sleep, the eyes move around quickly. The first REM phase takes place within approximately 90 minutes after dozing off. It is comparatively shorter in duration with the first REM being only about 10 minutes. As the night progresses, REM sleep gets longer. The sleep cycle ends with REM. The brain activity in this period resembles that of a wakeful being but limb muscles are paralysed. This is the point where dreams are seen. Heart and breathing rates become irregular. It is best to wake up between cycles rather than in the middle of one to feel recharged and alert. An individual completes 5-6 such cycles in a typical night.

It is astonishing that neuroscientists are still fully not clear on the need of sleep. However, sleep is important as research has proven people function better after a good night’s sleep. Memory retention, repair of tissues and muscle growth all take place when asleep. Sleep-deprivation can severely stress the mental health and affect hormonal balance. Sleep disorders like insomnia has been linked to diabetes and can worsen symptoms of depression and anxiety.


Hiya Islam is a student of BRAC University.



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