Why do we need to sleep?

Sleep is very important to our body. We tend to think of sleep as a time when the mind and body shut down.One of the vital roles of sleep is to help us solidify and consolidate memories. As we go about our day, our brains take in an incredible amount of information. Rather than being directly logged and recorded, however, these facts and experiences first need to be processed and stored; and many of these steps happen while we sleep. Overnight, bits and pieces of information are transferred from more tentative, short-term memory to stronger, long-term memory—a process called "consolidation." Researchers have also shown that after people sleep, they tend to retain information and perform better on memory tasks. Our bodies all require long periods of sleep in order to restore and rejuvenate, to grow muscle, repair tissue, and synthesize hormones.


One of the most recent and compelling explanations for why we sleep is based on findings that sleep is correlated to changes in the structure and organization of the brain. This phenomenon, known as brain plasticity, is not entirely understood, but its connection to sleep has several critical implications. It is becoming clear, for example, that sleep plays a critical role in brain development in infants and young children. Infants spend about 13 to 14 hours per day sleeping, and about half of that time is spent in REM sleep, the stage in which most dreams occur. A link between sleep and brain plasticity is becoming clear in adults as well. This is seen in the effect that sleep and sleep deprivation have on people's ability to learn and perform a variety of tasks.Several studies show that the light bulb has led people shifting their day and getting less sleep. On average we go to bed and wake up two hours later than a generation ago.

The US Centres for Disease Control reported in 2008 that around a third of working adults in the US get less than six hours sleep a night, which is 10 times more than it was 50 years ago. In a later study it was also reported that nearly half of all the country's shift workers were getting less than six hours sleep.

And a study led by Prof Charles Czeisler of Harvard Medical School found that those who read electronic books before they went to bed took longer to get to sleep, had reduced levels of melatonin (the hormone that regulates the body's internal body clock) and were less alert in the morning.

At the time of publication he said: "In the past 50 years, there has been a decline in average sleep duration and quality.

"Since more people are choosing electronic devices for reading, communication and entertainment, particularly children and adolescents who already experience significant sleep loss, epidemiological research evaluating the long-term consequences of these devices on health and safety is urgently needed."

Sources.
https://sleepfoundation.org/excessivesleepiness/content/why-do-we-need-sleep
http://healthysleep.med.harvard.edu/healthy/matters/benefits-of-sleep/why-do-we-sleep
http://www.bbc.com/news/science-environment-32606341