An article posted on Step to Health said that every activity or habit a person performs associates different segments and sections of the body. According to studies, the most crucial among all the parts is the brain because it controls numerous organs and regulates various actions and processes present in the body. 
These habits may enormously create a certain impact on the health condition and functions of the brain and also, the several organs that it controls. Therefore, if the habit is bad, some complications like degenerative disorders may occur over time, even without the person knowing it.
These are some of the Bad Habits that slowly damage and destroy the brain:
A. Alzheimers.net aforementioned that lack of sleep may plausibly lead to Alzheimer’s Disease (AD) because the brain’s waste-draining system, named as the glymphatic system which cleans the plaque-forming protein called amyloid beta is ten times more active during sleep.
B. Researches had also revealed that having too much time alone and isolation can cause depression, Alzheimer’s, and other ailments.
C. Experts from the University of Pennsylvania said that staying too much in the dark or light deprivation can actually cause neuronal death. The study involved numbers of rats kept in the dark for six weeks for the experimentation. It was seen that some of the candidates manifested depressive behaviors, less amount of norepinephrine, dopamine and serotonin in the brain, in accordance with the article posted on Scientific American.
D. Medical Daily stated that eating too much junk foods is unhealthy to the brain as well, because too much fatty food and sweet intakes can increase the insulin levels in the body. As a result, the body will have a hard time responding to hormones, may rot the individual’s memory box, lowers the ability to think accordingly, and may link to other alarming mental health issues.
Some studies also suggest that this habit is also relevant to eating too much food, that also causes obesity and heart illnesses.
E. Blasting Headphones- this habit does not only make a person suffer from hearing loss, but also, the loss of brain tissues. In fact, there is an article posted on hearit.org that mentioned loud noises can damage the nerves in the brain.
F. As a common knowledge, exercise keeps the entire body, including the brain very healthy. According to studies, sitting all day long or not moving enough will make your brain less active and less sharp.
G. Some studies discovered that smoking may shrink the brain, worsen the memory, increase the risk of Alzheimer’s, stroke, high blood pressure, and heart disease. Also, according to an article posted on New Science, nicotine kills and prevents the brain cells from forming new ones in the hippocampus and blocks some of the communication pathway, and may link to other problems.
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