November 29, 2011

The Collegiate Sleep Schedule: Finding Rhythm

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Circadian rhythm allows the body to predict when important daily events should occur, such as sleeping and eating. While our bodies try to maintain a steady circadian rhythm, in college it is easy to develop an out-of-sync clock, which may affect students’ ability to perform and maintain good health.According to Prof. James Maas, psychology, bodies are driven by multiple circadian rhythms. These rhythms include blood pressure, internal temperature, breathing cycles, and sleep. Maas pins the sleep and wake cycle as the most pertinent to college students who may exhibit yo-yo sleep patterns and delayed wake syndrome.Circadian rhythms differ from person to person, and the rhythm changes depending on age and diet. The best way to maintain a steady circadian rhythm: “Find your natural rhythm and stick to it. Try to stick to the same sleep and wake times,” said Anand Vaidya, a graduate student in the department of chemistry and chemical biology.Maas’ recommendation is similar. He suggests that even when one goes to sleep hours after their typical bedtime, they wake up at the same time in the morning, taking a power nap during the day if they are exhausted.“These cycles are pernicious, but can be changed over time with consistency,” Maas said.Many find themselves functioning against their set circadian rhythm, which is determined by the superchiasmatic nucleus, or SCN,  in the brain. According to Vaidya, the SCN can be thought of as the “master clock.”“The whole body is like an orchestra; everybody has their own piece that they play, but there is a conductor who puts everybody in sync. This master clock is the conductor,” Vaidya said.With so many different coordinating rhythms taking place in the body, it can be difficult to determine exactly what the optimum circadian rhythm is and how our daily activities interfere with the cycles. For example, one may question how their circadian rhythm is affected by exercising early in the morning versus at night.  Vaidya’s advice is to keep your own rhythm, doing the same things at the same times every day.“The time [at which you work out] doesn’t matter –– just try to keep that time constant across days. We need to observe how our bodies react to things and change accordingly. We can’t say definitively ‘this works’ and ‘this doesn’t work’- it is different between people,” Vaidya said.Often, the rhythms in the body are connected. For example, melatonin secretion is controlled by our clock, or circadian rhythm, and this clock is controlled by light exposure.Light travels to photoreceptors in the body, such as the retinas, which send signals to the brain depending on the shape of the protein and its capability to bind to sites that transmit these signals.Delayed wake syndrome may be the reason why many adolescents fail to fall asleep at 10 p.m., even if they are willing. As explained by Maas, a growth hormone is secreted late at night in adolescents that blocks the secretion of melatonin, a hormone that aids sleep.In these cases, students are not able to fall asleep until later hours yet still wake up early for class. “We have their bodies in the classroom but their minds are back on their pillows,” said Maas. “ The brain is not cognitively functioning under minimal sleep,” he continued.According to Maas, one’s circadian rhythm does not change unless time zones are crossed. Air travel has been a major contributor to the disruption of circadian rhythms. “Seventy years ago, transportation was not very fast. Everyone was in their own world. When they did travel, they took ships which provided very slow, gradual change,” Vaidya said.Flying across time zones confuses our circadian rhythms that operate on approximately 23.5-24 hour cycles. The body responds as if it is still in its home time zone, feeling hungry and tired at times that are not the same in the new time zone.Those who work the graveyard shift may be doing the most damage to their bodies, working against their natural circadian rhythms, getting reduced hours of sleep during unconventional times during the day. “The graveyard shift is a probable cause of colorectal and breast cancer,” Maas said. “I don’t know a single shiftworker who isn’t a walking zombie,” he said.The ability to develop a circadian rhythm has proven to be an evolutionary advantage in fruit flies, as well as other organisms.  When fruit flies evolved millions of years ago, the ozone layer did not exist, and ultraviolet radiation that entered the atmosphere harmed their DNA. Thus, it was pivotal to their survival and reproduction that they replicate their DNA at night. The organisms’ circadian rhythm allowed them to anticipate day and night cycles.Vaidya has been studying circadian rhythm in fruit flies and fungus at Cornell for the past five years. Recently, Vaidya and his colleagues were published in Nature, for their discovery of the structure and function of the protein cryptochrome, dCRY.dCRY is responsible for day and night cycles as well as magnetic field cycles in fruit flies. The protein’s function in other organisms is not yet fully understood. “[The article in Nature]  was a major breakthrough- knowing the structure of the protein allows us to modify the protein and see what is responsible for which function,” Vaidya said.

Original Author: Paige Roosa