Why do we Sleep?

Like many systems that operate on fuel and are in constant motion, the human body needs rest. Of course, the difference is that parts are not so easily replaced with our complex bodies. Sleep is the most important type of rest we can get. But the real key to understanding why we sleep is: knowing how animals came to sleep in the first place.
One study indicates that as animals evolved over time they learned to sleep/rest when it was safe to do so and when they couldn’t use their time to get food or to mate and increase the species. In addition, when the body indicated that it was weakened by activity or lack of food the animal simply had to rest (hopefully in a safe location) to build strength necessary to survive.

Another theory of sleep focuses on the body restoring and rebuilding during sleep, something that it can’t do when the animal is resting but still awake. This research shows that our bodies go through some unique processes of restoration that can’t occur unless the brain and major systems of the body are truly asleep.

However, these two schools of thought are still somewhat at odds on the truth in this matter. Both sides of the discussion admit that there is a real biological benefit from sleep that isn’t available to us when we are simply resting (even with our eyes closed). One of the areas that might help the two schools agree involves building new connections within the brain itself, something that can’t happen unless the entire body is in a state of deep sleep. The benefits may also involve rebuilding cell damage from everyday wear and tear.

One area of sleep study compares how much time is spent sleeping and how much time is spent in useful activity such as obtaining food and socializing with others of the species. In the opinion of some scientists, there should be an optimal amount for both. They should be in the right proportions.

This theory notes that certain animals wouldn’t benefit from being awake more than a few hours so they sleep a vast majority of the time. Some bats sleep 18 to 20 hours out of 24. Cats usually sleep 16 hours a day. According to this theory, they don’t need to be awake any more than this. If this is the case, then humans “need” to be awake approximately 16 hours a day to do what they need to do.
However, some animals don’t sleep at all. Biologists have found that whales and dolphins don’t really sleep at all. Some studies of sharks indicate that they cannot stop swimming or they will die. Thus, they may not sleep either. This could mean that these animals don’t need restorative sleep time, as one of the above theories indicates. Their bodies and brains may go into some sort of slower pace that provides all the rest they need. The answer to our question isn’t fully settled, but research has given scientists and the general public a much better idea of what sleep means to living things.