“Let’s say that we’re explaining sleep to an alien race that doesn’t sleep, and here’s what we say: ‘oh hey I’m having a great time hanging with you alien civilization, uh, but pardon me. I have to go be unconscious for eight hours and have vivid hallucinations'” says Ben from the YouTube channel BrainStuff- HowStuffWorks. Although Ben states that sleeping is a state of unconsciousness, it is actually not a time where the body goes dormant, but rather a different state of consciousness (Green). Dreams are one example of brain functioning during sleep, and even though scientist don’t have a consensus on why we sleep, the Division of Sleep Medicine at
Harvard Medical School has several developing theories:
1) Inactivity Theory
*All images are credited to Google
Although not favorable by most scientists, this theory suggests that animals sleep to stay still and quiet. Animals, vulnerable to predators, would be hidden and clear of a predator’s path, and would not call attention to themselves.However, a simple counter-argument is the ability of being able to react when threats are close by (“Why Do We Sleep, Anyway?”).
2) Energy Conservation Theory
If you sleep, you save more energy because of the lack of movement; metabolism in humans is reduced by as much as ten percent. This means both body temperature and caloric demand decrease during sleep. (“Why Do We Sleep, Anyway?”) However, Russel Foster conducted an experiment where he compared a sleeping person with an awake person who hadn’t moved much, and 110 more calories were burned in the awake person, which is the same measly amount as a hot dog bun. Therefore, this theory, like the Inactive Theory, is unfavorable to most scientists.
3) Brain Processing and Memory Consolidation Theory
After learning certain task, sleep deprivation smashes the ability to learn that task. On the other hand, a good night of sleep hugely enhances “the ability to come up with novel solutions to complex problems…In fact, it’s been estimated to give us a three-fold advantage. Sleeping at night seems to enhance our creativity” (Foster). What happens is during the night, synaptic connections connect and strengthen, while less important connections fade away.
4) Cerebrospinal Fluid Theory (CFT)
One of the newest breakthroughs of sleep occurred about a month ago: the CFT. In the diagram to the right, the lymphatic system (the system that carries cells’ wastes out) is shown to cover most of the body except the brain. Why would one of the most important organs with every cell supported with blood vessels have no lymphatic nodes to clean away its wastes? This is because the area in the brain is too compact to have extra channels, so it uses cerebrospinal fluid instead. Cerebrospinal fluid “is a watery fluid that is continuously produced and absorbed and that flows in the ventricles within the brain and around the surface of the brain and spinal cord” (“Cerebrospinal Fluid.”). This fluid is used to clear out the wastes in the brain; however, this can only be achieved when asleep. Jeff Lliff gives a great explanation of the use of CFT.
Bowlin, Ben. “Why Do We Sleep.” YouTube. Youtube, 21 March 2014. Web. 05 Dec 2014. <https://www.youtube.com/watch?v=ZCbCra-Mdy8
“Cerebrospinal Fluid.” MedicineNet. MedicineNet, 19 March 2012. Web. 06 Dec. 2014.
Foster, Russel. “Russell Foster: Why Do We Sleep?” YouTube. YouTube, 14 August 2013. Web. 02 Dec. 2014. <https://www.youtube.com/watch?v=LWULB9Aoopc
Green, Hank. “To Sleep, Perchance to Dream – Crash Course Psychology #9.” YouTube. YouTube, 31 March 2014. Web. 03 Dec. 2014. <https://www.youtube.com/watch?v=rMHus-0wFSo
Lliff, Jeff. “Jeff lliff: One More Reason to Get a Good Night’s Sleep.” YouTube. YouTube, 13 October 2014. Web. 06 Dec. 2014. <https://www.youtube.com/watch?v=MJK-dMlATmM
“Why Do We Sleep, Anyway?” Healthy Sleep. Division of Sleep Medicine at
Harvard Medical School, n.d. Web. 07 Dec. 2014. <http://healthysleep.med.harvard.edu/healthy/matters/benefits-of- sleep/why-do-we-sleep