By Anna Christou
While participating in sports improves physical activity and hones skills, such as teamwork, discipline, and hard work, playing contact sports, especially football and wrestling, can come at a cost—an increased risk of head injuries that can have long-lasting effects. According to the Brigham Health Hub, for people between ages 15 and 24, participation in sports is the second most common cause of head injuries, after motor vehicle accidents. In particular, the two most common head disorders that result from sports are concussions and chronic traumatic encephalopathy (CTE). Although doctors initially thought that CTE arose exclusively from concussions, a recent study found that hits to the head can cause CTE, even in the absence of a concussion. This study revealed that taking steps to reduce head trauma in sports is crucial, and merely treating concussions when they arise is not necessarily the most effective way to prevent the long-term cognitive deficits of head trauma.
Concussions affect a large number of athletes every year, with 1.6 to 3.8 million sports-related concussions occurring annually in the United States, according to a study published in Translational Research in Traumatic Brain Injury.
Normally, the brain is cushioned by cerebrospinal fluid, a substance with a gelatin-like consistency that protects the structure of the brain from the everyday movements that cause the brain to bump against the skull. However, a violent collision or rapid acceleration of the head, such as that caused by a hit during sports, is no match for cerebrospinal fluid. Head trauma of this degree can cause the brain to collide forcefully against the walls of the skull, often resulting in brain hemorrhaging, headaches, ringing in the ears, confusion, fatigue, and a temporary loss of consciousness. These symptoms result from a variety of changes to the brain on the cellular and molecular level, that are catalyzed by the trauma. Specifically, the impact disrupts cell membranes in the brain, leading to the release of ions and neurotransmitters that promote the excessive firing of neurons. As a result, the brain attempts to increase the production of energy in order to meet the metabolic demand caused by this increased firing. This produces lactic acid, a byproduct of energy production, which leads to excess acidity in the brain, disrupts the normal functioning of the brain, and leads to cognitive deficits. Also, inflammation from the trauma may cause axons—projections from nerve cells that are involved in the conduction of nerve impulses—to lose shape and degrade.
Recovery is very slow in the injured brain, since energy production is impaired and blood flow is reduced, impeding the flow of oxygen and nutrients that are necessary for the healing process. As a result, concussions, especially severe ones, can leave people with symptoms for weeks or even months, during which they cannot participate in physical activity, view screens, or be exposed to bright lights. In addition to these relatively short-term effects, the National Center for Health Research has stated that concussions can have long-term effects, such as a heightened risk of neurodegenerative diseases, including Alzheimer’s Disease, Parkinson’s Disease, and CTE, due to the permanent damage to the brain during the injury.
CTE, according to the National Center for Health Research, is a brain disorder that results from repeated head injuries and results in symptoms such as memory loss, impaired judgement, and depression. In essence, repeated hits to the head injure nerve cells in the brain, which conduct electrical impulses and are necessary for communication between brain cells. Consequently, areas of the brain atrophy, specifically the frontal cortex, which is involved in motor movements and executive functions, and the temporal lobe, which is involved in language processing. The hippocampus and amygdala, both sections of the brain that are involved in the production of memories, may also degrade. This very serious disorder affects many athletes, especially those who participate in contact sports. For example, a study published in the Journal of the American Medical Association analyzed the brains of 202 deceased football players and found that 110 of them had CTE.
Concussions and CTE have similar symptoms, but little is known about the relation between the two disorders: though repeated hits to the head can cause both concussions and CTE, not everyone who has a concussion necessarily develops CTE. Therefore, to further examine the links between head injuries, concussions, and CTE, researchers at Boston University studied brain injuries in humans and mice, and published a paper with their findings earlier this year in Brain: A Journal of Neurology. They first examined post-mortem brains of teenage athletes who had suffered head injuries and found evidence of brain damage, as compared to the brains of teenage athletes who had not had recent head injuries. For example, the brains of the athletes who had suffered from head injuries contained damage to small blood vessels and neuro-inflammation, which are symptoms of concussions. In a few cases, the researchers also detected changes to the Tau protein, an indication of CTE. Tau is a protein that stabilizes neurons, but if it is phosphorylated—a phosphate molecule is added—its function changes, and it is no longer able to effectively stabilize neurons. This results in brain degradation, because the neurons are not stabilized and the Tau proteins even accumulate into clumps that infect brain regions. High levels of phosphorylated Tau proteins are linked to both concussions and CTE, but the Tau proteins in the case of CTE accumulate and spread in a distinctive pattern that allows CTE to be identified.
Although the findings from the human study further elucidated the pathology of concussions and CTE, it is difficult to study to what extent head injuries such as concussions cause CTE, evident in post-mortem brains. Therefore, the researchers designed a mouse model of head injury, subjecting mice to unilateral impact, trauma that accelerates the head without deforming the skull. As a result, they found evidence of concussion-like symptoms very shortly following the injury. Specifically, the mice that underwent the trauma showed lower performance on the administered tests, which included beam-walking and other balance tests, suggesting that they had experienced neurobehavioral deficits as a result of the trauma. In addition to these acute concussion-like symptoms, the researchers found that many of the mice that underwent the trauma had brains that showed evidence of CTE, such as damaged blood vessels and injury to the blood-brain barrier, which is a network of blood vessels that keeps harmful substances from reaching the brain. Notably, researchers also discovered that although the concussion symptoms eventually resolved themselves, the long-term impairments in brain structure, such as inflammation, damaged Tau protein, and disruption of the blood-brain barrier, persisted. Mice that did not undergo any trauma did not show any cognitive deficits, such as CTE. These findings made clear that hits to the head can result in long-term brain damage, such as symptoms of CTE; however, not every concussion is necessarily followed by CTE. Moreover, in this study, the existence or severity of concussion symptoms was not correlated with these long-term symptoms. However, in the group of mice that did experience head trauma, CTE could still result even without symptoms of concussion. This finding does not detract from the severity of concussions but, rather, suggests that long-term deficits, including CTE, can be caused by hits to the head even in the absence of a concussion. Consequently, it is important to generally reduce head impact and hits in sports—not just try to relieve concussions when they arise.
Organizers of some sports teams have, to an extent, heeded advice from research findings such as that described above, and accordingly modified the rules to make playing safer. For example, the National Football League (NFL) moved the line at which players take kickoffs to shorten the distance over which opposing teams run towards each other, consequently lowering the speed upon impact. Also, the NFL recently implemented the crown-of-the-helmet rule, which penalizes football players who contact another player with the top of their helmet; hits between helmets cause the most injury and are closest to the brain. However, these rules to make play safer have been met with resistance from some players and coaches. For example, although some players have said that the issue of injuries should be addressed with safer rules, other players have remarked that playing in a violent way is part of football and that these rules will eventually take away from the essence of the sport.
Studies such as the ones described in this article raise awareness about the importance of preventing and properly treating head trauma, especially that which results from sports, rather than allowing violent hits and then treating concussions that arise. Even though a large number of athletes are affected by injuries, many continue to play without receiving adequate rest, and the persistence in associating football with violence has made hits so ingrained in the sport that implementing rules to ensure safety is difficult. However, if sports officials continue to ignore scientific evidence and recommendations regarding the dangers of head trauma, increasing numbers of athletes will suffer from long-term neural deficits that extend beyond the field.
By Clare Nimura
Are you tired? Whether you’re riding the subway, waiting in line at Ferris, or sitting down to do some work, lying down for a nap usually doesn’t seem like a bad alternative. Some people are supporters of the twenty-minute power nap, others try to align their nap with one sleep cycle, and yet others just pass out and wake up three hours later asking what day it is. Nap culture is rampant in our society, particularly on college campuses, where sleep often takes a backseat to work, extracurriculars, and time with friends.
The National Sleep Foundation’s 2018 “Sleep in America” poll indicates that only 10% of Americans prioritize sleep over other aspects of their lives, such as work, hobbies, and health and fitness, though the majority (65%) believe that sleep is important for productivity. According to the CDC, one in three American adults does not get enough sleep. Given these statistics, the constant wish for a nap is understandable. So how can we maximize the benefits of our naps? And how well can naps make up for a poor night of sleep?
Ideal nap conditions follow the Goldilocks principle: not too long, not too short. A nap should be longer than nodding off for a minute, but short enough that you do not experience severe sleep inertia, or grogginess upon waking. Sleep inertia occurs when you first wake up from deep sleep and levels of melatonin (a hormone that makes you tired) are still elevated. The best nap length to improve performance, alertness, and mood in healthy young adults has been suggested to be 10-15 minutes, according to studies at the Adelaide Institute for Sleep Health. This brief time ensures high performance immediately, rather than a slow fight against sleep inertia. Longer naps (~120 minutes, or one Rapid Eye Movement deep sleep cycle) contribute less to alertness but are useful for consolidating memories, especially ones tied to emotions. Different nap lengths have different benefits, so set your alarm wisely!
Other than duration, there are many factors that contribute to the perfect nap, one of which is when you sleep. For people who keep a relatively regular sleep schedule, the ideal time to nap is between 2-5pm. During this post-lunch slump, the body is using a lot of energy to digest food, and increased insulin levels can trigger the release of serotonin and melatonin, two molecules that are involved in regulating sleep. Your body’s internal clock, called the circadian rhythm, also makes it easier to fall asleep during this mid-afternoon window.
However, when you wake up from your perfectly-timed nap, are you “caught up” on sleep? Sadly, the answer is no. Napping mitigates but does not substitute for nighttime sleep. Most people don’t nap just for the fun of it, they nap to alleviate the host of problems that result from their lack of sleep. Sleep deprivation can weaken the immune system, impair memory, elevate stress levels, and increase the risk of car (or other) accidents. One of the greatest benefits of a full night of sleep is in memory, a complex process that is optimized during an extended period of sleep.
Before memories are cemented into our brain, they are consolidated. Memory consolidation is the process of stabilizing a new memory: parts of a memory are modified or deleted before the event is encoded to be stored in long term memory. On the cellular level, this process involves strengthening the connections between certain brain cells. The brain will store the most important elements of a scene or experience and discard some of the background details. This process happens most effectively during deep sleep, which is the first few hours of a full night of sleep.
A full, 7-9 hour night of sleep, always provides the most benefits in terms of memory consolidation, cognitive function, mood, and overall wakefulness, but a well-timed nap can provide a welcome boost in the middle of the afternoon. No matter the duration, naps have been proven to benefit cognitive performance, reasoning, reaction times and mood. The benefits from a nap are less variable and longer lasting than those from caffeine! However, while naps have been proven to provide benefits for memory, changing our attitude toward sleep and getting more sleep at night would be the most beneficial for our memories and most other aspects of our lives. In the meantime, though, while we make that shift toward prioritizing sleep, a nap is one of the best band aids for sleep deprivation.
Sleep, like food and water, is essential to maintain our physical and mental well-being. How has it slipped so far down our list of priorities? Over the past century, our society has grown to emphasize productivity and prosperity over leisure: Americans are working more, earning more, and spending more than in the past. This shift has been exacerbated by the rise of social media, which spreads unrealistic expectations of productivity. Hopefully, we are coming to the end of this trend. The growing body of research on the paramount importance of sleep and the escalating discussion of work-life balance are encouraging signs that we are rethinking our attitude toward sleep. So, go take a nap, but when you wake up, give some thought to how you can bump sleep higher up on your list of priorities.