By: Jeongmin Lee
Maybe it’s 10 in the morning or maybe it’s 2 o’clock p.m., but as soon as that professor starts his or her lecture, blackout. The natural circadian rhythm is severely altered throughout life. For many students, the sleeping cycle hits during class. While some people stay attentive all day working nine to five, others dip their heads five minutes after sitting down. With a scientific approach, we can ask what makes students fall asleep in class. Conversely, what factors keep their peers from nodding off? And, most importantly, are there any ways to stay awake without replacing our blood with coffee?
Human beings run on a sleep cycle, the circadian rhythm, which is managed by concentrations of hormones in our body. The endocrine system is responsible for a majority of the production of these hormones and the hypothalamic pacemaker controls our circadian rhythm (1). In the pacemaker, there are complexes such as the superchiasmatic nuclei (SCN) that have the period and cryptochrome proteins; the latter makes the system sensitive to light. These proteins activate the transcription of the CLOCK gene and gradually rise in concentrations throughout the day. When cryptochrome stops receiving light, transcription of the genes decreases eventually leading to the concentrations of the proteins to decrease as well. Through these different mechanisms, the body is able to signal a waking phase and a sleeping one. Over time, proteins degrade and create their own rise and fall without the cryptochrome’s light dependency. This creates a rhythm independent of the day and night cycle, which has a period of a little more than 24 hours. This means that a person with a circadian rhythm insensitive to light will get up a little later every day. However, other factors could come into play because the human body has multiple systems to control the sleep cycle. The MRC Laboratory of Molecular Biology has discovered that rhythmic glucocorticoid signals can significantly affect the SCN and internal clock. With this knowledge, the lab was able to connect irregular sleep with many other hormone-related issues such as abnormal tissue growth and blood pressure. That’s because the genes that code for period, cryptochrome, and clock proteins are all “E-box genes,” one of several gene sets that work in tandem with hormones such as glucocorticoid and other complexes to help regulate one’s biorhythm (1). There is a particular sleep-related hormone that is popularized by the news and pharmaceutical: melatonin.
Melatonin is a powerful regulation hormone that can induce alterations of a body’s circadian rhythm without depending on any other system. According to the Center for Chronobiology in Switzerland, melatonin can actually cause sleepiness. This makes melatonin a type of “chronobiotic” because it can shape the internal clock. Increasing melatonin levels correlate with decreasing sleep interruption. The circadian pacemaker that has the SCN, mentioned above, is linked to the production of melatonin. Melatonin is also sensitive to light, which causes the concentration of the hormone to decrease. While all light can inhibit melatonin secretion, studies show that blue light can inhibit the hormone – and therefore sleep – the most effectively (3). Thus, exposure to blue light when melatonin levels are supposed to be high can delay the circadian rhythm, keeping people awake. That is the reason why so many social media sites are blue and why they are so effective at passing time without the reader feeling tired. A shift in the circadian rhythm not only compels one to wake up later but also keeps him or her awake until late at night. Although how much harm low melatonin levels can do has not been fully analyzed, a displaced sleep cycle has been seen to “[increase] risk for depression, as well as diabetes and cardiovascular problems” (3). This science applies to people of all ages, but especially those who are experiencing hormonal changes.
Hormonal activity rapidly changes in the infamous period of puberty. Generally, teenagers have a later sleep cycle: their rhythm shifts an hour or two later than before.4 This change moves the timeframe of the rhythm rather than shortening it. Thus, the eight hours of sleep enforced on children are still required as they grow up. They only become inclined to sleep later in the day. Missing this rhythm leaves an adolescent fatigued. In the case of a student, focusing and studying throughout the day may become difficult. A common myth promises that he or she can “make up” missing sleep by sleeping in on the weekends. Although the average may even out to eight hours per day, sleep does not work like a savings account. As the body is programmed to run at a particular cycle, any deviation from the rhythm will prove to be detrimental which means that the people who sleep in “[throw] their body clocks off even more” (4).
Just as a lack of sleep can cause other health issues, other health issues can interrupt a normal sleep cycle. For example, obstructive sleep apnea causes the back of the throat to block the airway (4), while the more common shift work disorder causes insomnia while draining energy throughout the day (5). Narcolepsy, while varying in severity, can cause sudden sleep spells even when a person is actively moving. Finally, emotional changes and depression, which many adolescents struggle with, significantly disrupt sleep cycles. Such psychological effects on the circadian rhythm can be explained by the nervous system’s role in the body’s internal sleep cycle.
The brainstem is responsible for controlling sleep, like the hypothalamus is responsible for releasing hormones to maintain the circadian rhythm. Problems in the brainstem have been connected to the inability to sleep (6). That makes sense because the brain controls the majority of sleeping and dreaming behavior. Sleep requires a special pattern of brain activity, creating a dichotomy between two different types of sleep: “rapid-eye-movement (REM) sleep and non-rapid-eye-movement (NREM) sleep” (7). The former is believed to be the state when the person is dreaming, while the latter is a deeper sleep associated with the paralysis of the body. A healthy sleep oscillates between these two states, usually beginning with NREM and cycling with a period of approximately 90 minutes for adults (7). This cycle can also be shifted, which is unhealthy, due to the environment, stress, the circadian rhythm, and even alcohol and drug consumptions. There are also other parts of the nervous system that influence sleep. Many people feel tired after a meal, likely because of the autonomic nervous system. The autonomic nervous system commands “sweating, blood pressure, digestion, temperature” (6). The digestion has been correlated with activation of “sympathetic modulation of the heart” (8) which is interestingly also activated when the body is sleep deprived (9). The sympathetic nervous system is a part of the autonomic nervous system that generally controls involuntary actions such as digestion and cardiac movement. The two studies show that the heart is similarly activated by the sympathetic system after a meal and a lack of sleep. We talk about that effect with the phrase “food coma.” Despite all of these possible issues, not everybody falls asleep in class or in the library. How do teenagers ever stay awake despite all these hormones and systems obfuscating their sleep patterns, and are they staying healthy?
There are students who take the toughest classes, participate in late night ensembles, and practice sports at 4 in the morning without a single snore in their classes. Some of their methods appear more appealing than others. Some students who have morning rehearsals pack as much of their schedules into the morning as they can. After lunch, they can take a nap before moving on the rest of the day. Napping has shown to be a reasonable strategy to catch some sleep, but the constant wake-ups between five minute naps did not lead to a satisfying or effective way to “account for” the lost sleep. Many students drink coffee to wake up, or even take tablets of concentrated caffeine in the morning. An early dependence on caffeine cannot be beneficial — especially in an addictive dose. Finally, there are people that just go to bed early. They might go to bed around 8 o’clock while waking up before the sun comes up. This strategy not only allows for the required eight hours of sleep but also allows the student to do all of his or her work in the morning, starting the day refreshed. As it turns out, the best way to sleep is not deviating from a natural cycle with complicated systems, but rather adhering to what the body needs.
How do you follow your healthy sleep cycle? Matching day and night cycles can help in retaining a constant rhythm because most people have proteins such as cryptochrome that regulate the circadian rhythm by responding to light. Melatonin levels work similarly. Therefore, being in the light can keep one alert throughout the day. Conversely, exposure to as little light as possible near bedtime will increase the hormone’s concentration and help with falling into sleep, There are apps and programs for cell phones, tablets, and computers that offer a red light filter for the screen when the time gets too late. The red filter reduces the blue light that decreases melatonin levels the most; however, any light can decrease melatonin secretion so it is best not to stream television shows throughout the night no matter how red the screen is. If your sleep is interrupted by diseases such as obstructive sleep apnea, sleeping on the side can prevent airway blockage. Light therapy and small dosages of melatonin or caffeine can alleviate disorders such as shift work disorder. For everyone else, caffeine can be a way to stay awake; however, researchers recommend consumption of about 200 mg — about one cup of regular coffee. Any more can lead to severe shifts of the sleep cycle and addiction. Since eating late at night may interrupt sleep patterns, it is generally best not to eat past 10 pm or for a few hours before going to bed. Napping can often be a good idea, but people with insomnia are discouraged from doing so and an afternoon nap might lead to slipping into deep sleep through the whole night. A student’s life makes it difficult to adhere to all these guidelines, so there are political arguments calling for schools to operate at later times. To correlate with adolescent’s sleep cycle shifting later into the night, the “American Academy of Pediatrics (AAP) recommends middle and high schools delay the start of class to 8:30 a.m. or later” (10) due to the research suggesting how students are better fit later on in the day. It is especially hard for young adults to maintain a healthy sleeping schedule. That said, many adults struggle too: they still cannot fully shift their sleep cycle and maintain a healthy lifestyle. Hopefully, these tips can help students of all ages to hit the stacks without hitting the sack.
Jeogmin Lee ‘19 is a freshman in Hollis Hall.
 Michael Hastings, John S O’Neill, and Elizabeth S Maywood. Circadian clocks: regulators of endocrine and metabolic rhythms. J Endocrinol 195 (2) 187-198, 2007, doi: 10.1677/JOE-07-0378
 C. Cajochen, K. Kraüchi and A. Wirz-Justice. Role of Melatonin in the Regulation of Human Circadian Rhythms and Sleep. Journal of Neuroendocrinology, 2003, Vol. 15, 432–437
 Blue light has a dark side. Harvard Health Letter. Harvard Health Publications: Harvard Medical School, 2 Sept. 2015. Web. 26 Feb. 2016. ‹http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side›
 Sleep and Teens. UCLA Sleep Disorders Center. Web. 26 Feb. 2016. <http://sleepcenter.ucla.edu/body.cfm?id=63>.
 “What to Ask Your Doctor About Shift Work Disorder.” – Shift Work Disorder. Web. 26 Feb. 2016. <https://sleepfoundation.org/shift-work/content/what-ask-your-doctor-about-shift-work-sleep-disorder>.
 “Cognitive Skills of the Brain.” Brain Injury Alliance of Utah. Web. 26 Feb. 2016. <http://biau.org/about-brain-injuries/cognitive-skills-of-the-brain/>.
 “Natural Patterns of Sleep.” Division of Sleep Medicine at Harvard Medical School. 18 Dec. 2007. Web. 26 Feb. 2016.
 Kuwahara K, Okita Y, Kouda K, Nakamura H. Effects of modern eating patterns on the cardiac autonomic nervous system in young Japanese males. J Physiol Anthropol. 2011;30(6):223-31.
 Zhong X, Hilton HJ, Gates GJ, Jelic S, Stern Y, Bartels MN, Demeersman RE, Basner RC. Increased sympathetic and decreased parasympathetic cardiovascular modulation in normal humans with acute sleep deprivation. J Appl Physiol (1985). 2005 Jun;98(6):2024-32. Epub 2005 Feb 17.
 “Let Them Sleep: AAP Recommends Delaying Start Times of Middle and High Schools to Combat Teen Sleep Deprivation.” 25 Aug. 2014. Web. 07 Mar. 2016.
Categories: Spring 2016