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Is Sleep Deprivation the Cause of the 'Freshman Fifteen'

Emily Lynn Davies

Schlundt- Feb 23, 2010

For most people, twenty-four hours can only be stretched so far. With so much to do and so little time in our 24/7 society, something has to give way to our busy lifestyles. In recent years, that thing has been sleep. On the surface, it makes sense that in order to be productive one should forfeit their most unproductive time. However, American’s don’t realize what they are jeopardizing by giving up the few hours of sleep that could save one’s life, or if a college freshman, one’s sanity and physique. College is quite the environment to adjust to considering that it’s a whole new ball game- new people, new surroundings, and more challenging academia. College students stay up until the wee hours of the morning completing assignments and maintaining their social lives. For some reason it’s acceptable and, at schools such as Vanderbilt, inevitable, that college students will face the predicament of having to pull and ‘all-nighter.’ This borrowed time form sleep can negatively influence one’s awareness and productivity more than the average student knows. Students do not realize that sleep deprivation can lead to serious medical issues, failing grades, mental issues and in some extreme cases, even death. Is staying up to get work done worth the risk? With that being said, the commonly known “freshman fifteen” is doomed upon all incoming college students. Though increased alcohol consumption and social stress are suspected contributors to the weight gain of freshman college students, sleep, specifically lack thereof, is the overlooked root of the issue concerning poor adjustment to college life.

According to Eve Van Cauter (2007), University of Chicago’s leading sleep researcher, humans are the only animals that deliberately deprive themselves of sleep. In recent years, the average number of hours of sleep has decreased in Americans while the prevalence of obesity has significantly increased. In a study of college students’ sleep patterns, Tsai and Li (2004) found that women get anywhere from 5-7.5 hours of sleep per weeknight and about 6 hours of sleep on weekends. On the other hand, college age men were found to sleep anywhere from 6 to 7 hours per weeknight and less than 6 hours of sleep on the weekends. The hours of sleep students received were significantly lower on the weekdays than on the weekends (Tsai & Li, 2004). The observation that there students sleep less on the weekdays compared to the weekends could be due to the fact that school work during the week takes up a larger amount of time than social activities. Tsai and Li (2004) also observed that as students aged, the amount of sleep hey got increased. Freshman got the least amount of sleep, followed by seniors, but sophomores and juniors slept the most number of hours during the weekdays and the weekends. However, the significant gap between the amount of sleep freshman got compared to the amount seniors got was still respectively worthy of attention (Tsai & Li, 2004). Most college freshman do not have the best time management as they are not used to the routine of college life and the skill typically improves as students adjust.

We ignore sleep, even though it is just as crucial for our health as eating and exercise (Saey, 2009). What is sleep exactly? The behavior referred to as ‘sleep’ is a mystery to researchers all around. While asleep, one’s body remains still, but the brain is fully active. The effects of sleep deprivation are so hard to explain because the purpose of sleep is hard to define. Many scientists refer to sleep as ‘neural remodeling’ in which the brain processes memory and information. Some define sleep as the effect of being a complex organism in need of recharging. Other theories suggest that sleep’s purpose is to strengthen the immune system, regulate emotions, or save energy (Saey, 2009). However, studies show that ‘sleep’ is just as vital to metabolic systems as its opposite ‘wake’ is. Allan Pack from the University of Pennsylvania, conducted a study using mice to observe what changes occur when the mice’s slumber was disturbed. In this test, Pack concluded that sleep was a time for “replenishment and construction of cellular parts” (Pack et al., 2009). Pack (2009) further concluded that one sleeps “so [that] when wakefulness comes along, [one] has the building blocks to make synapses.” A synapse is the meeting of neurons in which signals flow to the brain, which then operates one’s body to function or perform a certain behavior. University of Pennsylvania’s Sehgal and Harbison (2008) tested this hypothesis that sleep alters metabolism by depriving fruit flies of their sleep and observing the effects of stimulation. When deprived of two hours of sleep, the flies’ were unable to make up the debt of sleep and, when physically stimulated, no matter what time of day, the result was a decreased store of glycogen and increased triglycerides (Sehgal & Harbison, 2008). These two substances, a starch and a type of fat, respectively, are both related to weight gain when increased or decreased as they were in the fruit flies’ case (Knutson et al., 2007).

When sleep deprived, one can seem irritable and don’t perform at full capacity. Nodding off in class or not being able to make it through the day can be a physical and immediate sign of sleep deprivation, however, there is an undetectable deterioration happening inside the body that leads to weight gain, which is not always immediately recognized (Van Cauter et al., 2007). Chronic sleep loss is linked to obesity due to the fact that when one does not get enough rest there are metabolic and hormonal ramifications. These include alterations in levels of leptin, ghrelin, glucose and insulin. Leptin is a hormone that regulates appetite; when leptin levels fall one’s appetite increases (Davila, 2009). Ghrelin is a peptide released from the stomach that generates a positive energy balance and increased adiposity by increased food intake and reduced fat oxidation and is shown to increase appetite and food intake (Knutson et al.,2007). Leptin and ghrelin exert opposite effects on appetite (Van Cauter et al., 2007). Thus, when one is deprived of sleep, since leptin decreases and ghrelin increases, one is likely to have a greater appetite. This explains the line at 2:00 A.M. for fourth meal that most Vanderbilt freshman make sure they get.

In a study conducted by Everson and Szabo (2009), consumption of food in sleep restricted rats increased 215% to 456%. The longer the rats were deprived of sleep, the more their food intake increased. In the end, the sleep restricted rats had significantly eaten more and gained weight. Everson and Szabo conclude that loss of sleep correlates to appetite and weight gain in an evolutionary sense. Thus, when one enters ‘survival mode,’ which is triggered by lack of sleep, the body will send out hormonal signals to eat more because eating, just as sleeping is, is essential to survival (Everson & Szabo, 2009). When college students stay up cramming for a test or writing a paper due the next morning, they are tricking their body in a “flight or fight” physiological response.

In correlation to an increased appetite and the need for a midnight snack, one’s metabolism is altered. When sleep is compromised, the thyroid gland is affected because thyroid stimulating hormone (TSH) levels are significantly depressed after days without adequate sleep (Knutson et al., 2007). In addition, levels of cortisol are significantly increased (Easton, 1999). Increased cortisol is linked to increased abdominal fat and a decrease in lean muscle tissue as it is a “flight or fight” stress hormone. It makes sense that in an evolutionary sense abdominal tissue would be more fatty than lean muscle in survival mode because muscle production requires more energy and fat is energy that is easily used.

According to Van Cauter (2007), one day after sleep deprivation the body’s metabolism of glucose resembled that of patients with type 2 diabetes. Thus, being on a lack of sleep is equivalent to being diabetic and well rested. When sleep deprived Van Cauter and colleagues (2009) also concluded that it took the participants’ forty percent longer than normal to stabilize glucose levels.

According to Van Cauter et al. (2009), “While the primary function of sleep may very well be cerebral restoration, our findings indicate that sleep loss also has consequences for peripheral function that, if maintained chronically, could have long-term, adverse health effects.” In other words, sleep has so many affects on physiological behavior and there are so many models on the complexities of sleep that it is hard to pinpoint any certain evidence that sleep deprivation is the main cause.

Of course, the studies mentioned above do support the idea that sleep is a factor in gaining weight in college and that, since freshmen are the most sleep deprived, they are the most susceptible to weight gain in college. However, since there are so many factors that that influence metabolism, more studies need to be done on sleep deprivation and weight gain especially in college age students.
Robert Stickgold of Harvard Medical School equates the application of sleep theories to a blind man describing an elephant; it’s a snake, a tree, or a wall, depending on which part of the elephant the man touches (Saey, 2009). The theory that sleep causes weight gain alone is inconclusive but it is indeed a significant factor in the weight gain of college freshman.

Van Cauter E, Holmbäck U, Knutson K, Leproult R, Miller A, Nedeltcheva A, Pannain S, Penev P, Tasali E, Spiegel K. (2007). Impact of Sleep and Sleep Loss on Neuroendocrine and Metabolic Function. Horm Res 67(1):2-9 (DOI: 10.1159/000097543)

Everson and Aniko Szabo. (2009). Departments of Neurology and Population Health, The Medical College of Wisconsin. 297: R1430 - R1440. (DOI: 10.1152/ajpregu.00230.2009)

Susan T. Harbison1 and Amita Sehgal (2008) Quantitative genetic analysis of sleep in Drosophila melanogaster. Genetics,178(4):2341-60 (DOI:10.1534/genetics. 107.081232)

Knutson K, PhD, Spiegel, PhD, Penev, MD, PhD, Van Cauter, PhD (2007) The metabolic consequences of sleep deprivation. Sleep Med Rev., 11(3) (DOI: 10.1016/j.smrv.2007.01.002. Saey (2009, October 24) The Why of Sleep. Science News, 176(9):16, 28.

Easton (1999, December 2) Lack of sleep alters hormones, metabolism. The University of Chicago Chronicle, 19(6).

Tsai and Li (2004) Sleep patterns in college students: gender and grade differences. Journal of Psychosomatic Research, 56(2):231-237. (DOI: 10.1016/ S0022-3999 (03)00507-5)


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