Why We Sleep, Essay Example

Humans need sleep for a variety of reasons; however this phenomenon is somewhat unknown. Of the many thoughts, scientists developed numerous theories that could potentially explain the fact that humans spend about one third of their life sleeping. The goal of sleep research is to assist people in better understanding the importance of sleep. Through this understanding would bring the ability to identify how sleep assists the body, as well as the benefits of a restful night of sleep! The purpose of this essay is to examine the most current theories of sleep for both humans and animals.

The first and most basic theory of sleep is known as the inactivity theory. This theory is the oldest and is also commonly known as the adaptive or evolutional theory. The basis of this theory revolves around the fact that humans as well as animals are more inactive at night time because of dangers that the dark brings. For animals, it is quite simple; the danger brings difficult sight and predators, which creates vulnerability. Obviously the animal that is dormant at nighttime fare better than others because of the loss to predators or accidents during the night time hours. This is also revolves around natural selection or survival mode. Like any theory there is a opposition point, which suggests that animals should remain conscious in order to be able to react to an emergency, even if lying still in the dark at night (Healthy Sleep). Clearly this opposition point suggests that the animal that is not conscious at night would do no good against predators.

“The energy conservation theory suggests that the primary function of sleep is to reduce an individual’s energy demand and expenditure during the time of day or night, especially when it is least efficient to search for food” (ibid.). This theory revolves mainly on the thought that animals must make the most of their energy resources and rest when it is most conducive. If well rested, obviously they wold have more energy and ability to hunt for and catch food. Because energy metabolism is decreased at approximately 10% for humans during sleep, this would also suggest that they could function better during normal waking hours. During sleep a person’s body temperature decreases and therefore reduces caloric demand.

The next sleep theory is known as Restorative sleep theory. This theory suggests that the body restores losses during sleep, meaning that it rejuvenates and replenishes. Importantly, “Sleep provides an opportunity for the body to repair and to rejuvenate itself” (ibid.). To further this theory many empirical studies have identified that there is a reduction of immunity protection in animals that have a loss of sleep within only a few weeks. In fact, these studies have shown that animals that are sleep deprived for a few weeks can actually die. This is because the body actually restores body functions such as muscle growth, tissue repair, hormonal and hormonal release, just to name a few. Sleep also has been shown to assist in the rejuvenating of the brain and also its cognitive functioning. During waking hour’s chemicals known as neurons are produced within the brain. These neurons are known as adenosine, which is a product of cellular activity within the brain. This by-product produces the effect of “tiredness” with in the individual or animal, which gives an indication that the organism needs essential sleep. It has been suggested that adenosine is directly responsible for the ability to or motivation to sleep. During waking hours, adenosine continues to increase and the levels remain high, however during sleep it reduces and even depleted. An example might be a student that stays up all night cramming for an exam the next morning. This is not a good idea, because they feel drained and tired the next day. Their body will desire sleep and they will likely perform poorly on the exam as a result. Products that have caffeine can assist in the person’s feelings or tiredness, as it works to block the actions of adenosine within the brain. By blocking, adenosine gives a measure of alertness as many a student has already discovered (ibid.).

Brain plasticity, was also explored, and is a theory that is not clearly understood. Even though it is misunderstood it is important to all. The most affected group of individuals that is affects is infants. Because infants have a great deal of plasticity, they are able to develop, however only in good health or conditions. Of these conditions, sleep is clearly one of the most important. Sleep is essential to an infant’s development. It is estimated and recommended that infants sleep between 13 and 14 hours per day. This allows for sufficient REM sleep, which is also important to the development of the child. The relationship between sleep and brain plasticity is being researched and also is said to have a negative effect for adults, just like infants. Research has shown there is also a negative effect for adults in relation to sleep deprivation, which hinders a person’s ability to learn and to perform new tasks (ibid.)

In order to determine the amount of sleep that an individual needs, the age of the person is taken into consideration. It is assumed that an adult would perform best with 7 to 8 hours of sleep, however this is a simple guide. Some adults need 9 hours or maybe less to function at their maximum. The difference in the need for sleep is based on the individuals “basal sleep need or the amount of sleep our bodies needs on a regular basis for optimal performance and sleep debt, the accumulated sleep that is lost due to poor sleep habits, sleep that is lost due to sickness, awakenings due to environmental factors or other causes” (National Sleep Foundation). It is also notable to mention that even though a person may get their basal sleep need one night or even several in a row, they may still be sleep deprived and even feel sleepy throughout the day.

Animals such as horses typically need only minutes to three or four hours of sleep during the night. Horses also engage in another two or three hours while standing daily. Foals typically sleep longer and deeper than an adult horse, which can be compared to an infants need for more sleep than an adult. It is not uncommon for horses, just like humans to develop a pattern or routine of sleep. This has been shown by monitoring horse’s behavior, one in particular known as Obie. During this show, Obie monitor or guard, noticed that Obie, seemed to be following a strict routine, which included sleep, kept a record and said he could set his watch by his routine. (Barber).

Dogs typically sleep more than humans and horses, combined and generally get about 12 to 18 hours per day. Just like humans dogs also engage in rapid eye movement (REM) and slow wave sleep. Dogs that are involved in tasks, like search and rescue typically sleep less than most domestic pets. It is assumed that they sleep less because of their high activity levels during the day. This might suggest that dogs sleep more out of boredom—just like people as well—but they know when to be awake and aware of their surroundings. People should also remember the expression, “Let sleeping dogs like,” and act accordingly unless there is a reason to wake them.

References

Baker, K & K. Hitting the Hay. Retrieved on May 10, 2012, from http://www.mirrorkbranch.com/article11.html.

Healthy Sleep. Why do we sleep anyway? Retrieved on May 10, 2012, from http://healthysleep.med.harvard.edu/healthy/matters/benefits-of-sleep.

National Sleep Foundation. Waking America to the importance of sleep. Retrieved on May 10, 2012, from http://www.sleepfoundation.org/article/how-sleep-works/how-much-sleep.

The Dog Bowl. Why do dogs sleep so much? Retrieved on May 10, 2012, from http://www.thedogbowl.com/PPF/category_ID/O_140/dogbowl.asp.