Why do we sleep?

You snooze, you lose. It’s a catchy phrase. But sleep is not an optional enterprise. All mammals do it. So do birds, reptiles, and even fruit flies. Rats deprived of sleep apparently die faster than those deprived of food. In spite of these facts, we know very little about the purpose that sleep serves for us. Why do we sleep?

After sleeping over this question, I went in search of some theories. I came across a few. But first, let’s first get to know the two different types of sleep. “Two different types!” Initially, I was surprised as well.

A little more than a half-century ago, most scientists believed that sleep was an inactive state. Then in 1951, Eugene Aserinsky, a clever graduate student at the University of Chicago, hooked his son Armond to a retooled "brain wave machine" and monitored the boy's sleep deep into the night. Aserinsky observed sharp spikes of activity on his readout, suggesting that Armond's eyes were darting back and forth. This turned out to reflect the distinctive state within sleep dubbed rapid eye movement, or REM. Latter it was hypothesized that this movement was related to dreaming. When we are not dreaming but still sleeping, we are in NREM sleep, or Non REM sleep.

Now that we have familiarized ourselves with the two types, let us try and answer the question.

With sleep, as opposed to food, no one knows exactly what the underlying need is. However, to understand its relevance in simple terms, let us think of our bodies as a car. I presume everyone here, other than me, owns a car, or do I have company? Now you will all know that no car can keep going and going without a tune up or oil change. Well, the car may still run, but not as smoothly as it would have done if maintained properly. Scientists believe that sleep is like a daily tune-up for our bodies.

Now to get back to the theories: There are three theories that I am going to talk about today. The first among them is the Repair and Restoration Theory:

According to this theory, sleeping is essential for revitalizing and restoring the physiological processes that keep the body and mind healthy and properly functioning. This theory suggests that NREM sleep is important for restoring physiological functions, while REM sleep is essential in restoring mental functions.

Support for this theory is provided by research that shows periods of REM sleep increase following periods of sleep deprivation and strenuous physical activity. During sleep, the body also increases its rate of cell division and protein synthesis, further suggesting that repair and restoration occurs during sleeping periods.

The second theory is the Evolutionary Theory:

This theory is also known as the adaptive theory of sleep, suggests that periods of activity and inactivity evolved as a means of conserving energy. According to this theory, all species have adapted to sleep during periods of time when wakefulness would be the most hazardous.

Support for this theory comes from comparative research of different animal species. Animals that have few natural predators, such as bears and lions, often sleep between 12 to 15 hours each day. On the other hand, animals that have many natural predators have only short periods of sleep, usually getting no more than 4 or 5 hours of sleep each day.

The last theory that we are going to talk about is the Information Consolidation Theory:
The information consolidation theory of sleep is based on cognitive research and suggests that people sleep in order to process information that has been acquired during the day. In addition to processing information from the day prior, this theory also argues that sleep allows the brain to prepare for the day to come. Some research also suggests that sleep helps cement the things we have learned during the day into long-term memory. Support for this idea stems from a number of sleep deprivation studied demonstrating that a lack of sleep has a serious impact on the ability to recall and remember information.

While there is research and evidence to support each of these theories of sleep, there is still no clear-cut support for any one theory. So, although we haven’t answered the question directly, we now know that the stigma of laziness that comes with napping is not justified. I hope that from now on, everyone here will ensure that they get proper sleep everyday, particularly people who are involved in hectic physical or mental activities. These include mothers, (and fathers in some cases), industrial workers, doctors and many more. Remember, you snooze, you achieve.