Why Do We Sleep?
The average person spends a third of their life sleeping, which amounts to approximately 229,960 hours of their lifetime. Sleep is a vital process humans have performed ever since our existence on this planet, and it is critical to our survival. Many believe that sleep is important because it allows the brain to shut down for a period of time and rest. However, scrutiny of the brain during sleep shows otherwise – it is surprisingly active during this time period, performing many different activities. Given this finding, what is the purpose of sleep if not for suppressing brain activity?
Four theories are to be referenced to better understand why we require sleep. According to the brain plasticity theory, sleep is a vital process for the development of the brain and neurons. While asleep, neural networks reorganize and the brain adapts to new skills or information acquired during the day. The brain solidifies memories and eliminates unwanted information or wastes that have accumulated in the cells. This improves learning, concentration, memory, and the performance of various other cognitive functions that are essential in our day to day lives. Infants sleep for longer amounts of time and learn at a faster rate than adults because their brains are developing and adapting to their surroundings.
However, the functions of sleep extend far beyond the brain as it engages in a plethora of other processes. In fact, recent research on hydra vulgaris, a primitive organism that lacks a brain and a nervous system, reveals that sleep is not a function confined to species with a brain. This leads scientists to hypothesize that sleep has evolved before brains and has a much more fundamental and influential role in sustaining life on Earth. The adaptive function theory suggests that sleep has evolved as a form of protection against danger. When asleep, organisms appear less evident in their environment which protects them from being caught by predators.
The energy conservation theory explains how the amount of energy one has to spend is regulated by the decrease in metabolic rate when asleep. This decrease allows us to rely on a smaller amount of food for survival, as it used to be significantly more challenging to hunt for food at night. Lastly, the restorative theory indicates that sleep is a necessary mechanism for cell development, repair, and recovery. During the state of sleep, tissues are repaired, hormones are released, and essential proteins are produced. These processes revitalize the body and mind in preparation for the beginning of a new day.
Sleep is a universal process exhibited by all organisms, and there are several theories that support its importance and value. Despite the knowledge that sleep serves a number functions, this phenomenon contains many nuances that make it a topic of ongoing research to further solidify our understanding of this complex process.
Written by Thulashini
References:
https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-science-of-sleep-understanding-what-happens-when-you-sleep
https://www.sleepadvisor.org/history-of-sleep/
https://www.healthline.com/health/why-do-we-sleep#emotional-health
https://www.medicalnewstoday.com/articles/medical-myths-the-mystery-of-sleep#1.-Your-brain-shuts-down-during-sleep
https://aeon.co/essays/a-quantitative-theory-unlocks-the-mysteries-of-why-we-sleep
https://www.kyushu-u.ac.jp/en/researches/view/196/
