Understanding the Teenage Circadian Shift or Sleep Wake Cycle

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"Understanding the Teenage Circadian Shift or Sleep Wake Cycle"
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It is 8:00 a.m. Many American high school students have already been in school for 45 minutes, yet, according to sleep research, the teenage brain does not "wake up" until later in the morning, closer to 10:00 a.m. Why bother going to school for two hours if the brain is not sufficiently prepared? Students and teachers ask themselves this question daily. Psychologists have discovered that the Circadian Rhythm or Sleep-Wake Cycle of Teenagers is vastly different from that of an adult. Is it logical to assume that high school students would perform better in school if the hours accommodated their biological clocks? This paradox of sleep and education requires a change if students are expected to rise above their current achievement level.
Consider an average teenager's schedule: after waking up at about 6:00 a.m., he rushes out the door to catch the school bus at 7:20. School begins promptly at 7:50. After a Calculus test in his first hour, he is caught dozing off in his second hour, World History. After school, there is play practice until 5:00, then a swim meet. At 9:30 that night, homework begins. At 12:00, his mother forces him to go to bed. Unfortunately, he could not quite reach the required 1500 words on his English essay, so he will have to wake up 30 minutes earlier the next morning to finish it. If every day is similar to this, the example student is getting about 6 hours of sleep per night.
I have witnessed the effects of the delayed Teenage Sleep Cycle firsthand. As a senior in High School, I have spent many a late night sitting at the computer, trying to
finish impending assignments. Accompanied by an early wake time, I estimate that I lose about two hours each night. After a rough six hours of sleep, I am difficult to wake, and find myself hitting the snooze button more than once each morning. At school, I notice, especially in my first two classes, that I am very tired. Sometimes I cannot fight the urge to close my eyes, and I sleep in class. My teachers notice the effects of the Circadian Shift. On the days when I have two hours of math in the morning, my teacher has pointed out an almost instantaneous "awakening" of my peers and myself.
When we sleep, our brain has time to rest, recharge, and make sure that all parts of the body are working efficiently. Sleep is divided into four chronological stages, which can be seen by a difference in wavelength and shape on an Electro encephalograph (EEG). Stage 1 is light sleep, characterized by twitches and other reactions to external stimuli. Alpha waves, which characterize being awake, gradually turn into theta waves. Stage 2 is when "sleep spindles" appear on an EEG. In stage 2, consciousness of surroundings completely disappears. Stage 3, or delta waves, is very short, and a transition into Stage 4. True Delta Wave sleep, or Stage 4, is the deepest sleep. After Stage 4 is REM sleep, or Rapid Eye Movement. In this, the most important stage, the eyes twitch rapidly, hence the name. It is also when dreams occur, which are taken randomly from the subconscious. During REM, the body goes through a checklist of sorts, testing the vital organs, including stimulation of the genitals, to ensure that copulation is still possible. REM sleep is very important to the sleep cycle, and a lack of REM increases the effects of sleep deprivation.
The Circadian Rhythm, a term coined by Franz Halberg, is the 24-hour sleep/wake cycle. The Circadian Rhythm is based on cycles of light and darkness, which in turn tell us when we should sleep or be awake. Circadian Rhythms are believed to have originated in the earliest cells. In single-celled organisms, the Circadian Rhythm protects DNA from being damaged by ultraviolet rays, by only allowing the cell to replicate DNA at night, when there are significantly fewer ultraviolet rays. According to a study conducted by the National Institute of Mental Health, a group of mice who lacked a gene for photopigment melanopsin showed an impaired ability to regulate their natural clocks naturally. This gene, which affects the eye, reduced the correlation between light and sleep cycles (Science Daily).
To many adults, 6 hours of sleep sounds reasonable. However, it is nowhere near enough for a teenager. Psychologists have identified a shift in the body clock from child to adolescent, at about age 12 or 13. While an adult can sleep seven hours and wake refreshed for the day, seven hours equals sleep deprivation for a teenager. This shift can also be seen in adults, when it returns to a rhythm similar to that of the younger child. In fact, Psychologists recommend that adolescents sleep for nine hours fifteen minutes each night to be completely rested, more than any other age group, save infants.
The Circadian Shift is believed to occur in the first stages of puberty, when young adolescents undergo rapid growth spurts and body modifications. To help the body recover from these drastic changes, the Pineal Gland in the brain releases melatonin, the hormone that makes humans feel tired. In his book The Promise of Sleep, Dr. William C. Dement explains that pubescent sex hormones also affect the sleep cycle. These hormones include testosterone, follicle-stimulating hormone, and leuteinizing hormone. These three hormones are released in small amounts during childhood, but not at any particular time. In Puberty, the release time is regulated, and these hormones are released in large amounts when the adolescent is sleeping. When the release of melatonin is reduced or delayed, puberty is said to begin. When the Circadian Shift takes effect, the adolescent does not feel tired at the time that parents consider a "normal bedtime"-about 10:00 p.m. The teen is simply not biologically ready to sleep. If he is forced to go to bed at this time, it is very likely to stay awake-reading, watching television, or simply staring at the ceiling until midnight or later, when the adolescent biological clock triggers sleep. Personally, this is a nightly occurrence. I am told to go to bed sometime between 10:00 and 10:30, and do not actually fall asleep until 11:30 or midnight.
Another pattern often seen in adolescents is an irregular sleep schedule. To make up for sleep lost during the week, most teenagers sleep in on weekends. One study showed that sleep time increased by an average of one hour fifty minutes on Saturday and Sunday (Wolfson and Carskadon, 1998). In 18 and 19 year-olds, the sleep time increased at least two hours.
For some reason, adults do not seem to understand the significant difference between an adults' sleep cycle and the cycle of an adolescent. According to the 2006 National Sleep Foundation's "Sleep in America" Poll" Nine out of 10 parents believe their adolescent is getting enough sleep at least a few nights during the school week, leaving an 'awareness gap' between parents and teens" (NSF-Sleep in America). At the end of adolescence and the beginning of adulthood, which usually takes effect at age 18 or 19, the body clock shifts again. The amount of necessary sleep declines with age, and the wake time gradually gets earlier. For example, my grandmother is asleep by 9:00 p.m. and up at or before 6:00 a.m. Apparently, adults forget that their body clocks were once different, and try to force the adult sleep schedule on us adolescents. Combined with an early school start time and heavy workload, not to mention nutrition and other health factors, the youth of today are less healthy than ever.
One of the pioneers of adolescent sleep research is Mary Carskadon, Director of Chronology and Sleep research at the Brown University School of Medicine. She has conducted many studies on adolescent sleep, one of which was conducted on 3120 students at three Rhode Island high schools. This study identified a correlation between quality and quantity of sleep, and school performance.
According to a report done by the National Sleep Foundation (NSF) on adolescent sleep requirements "Sleep, in essence, is the food of the brain, and insufficient sleep, can be harmful, even life threatening." Sleepiness leads to a reduced level of alertness and ability to be attentive. Other effects of excessive sleepiness include reduced short-term memory, moodiness, and behavioral control, all of which greatly affect school performance. In a study conducted by Dr. Amy Wolfson and Dr. Mary Carskadon, students who identified themselves as struggling high school students, earning Cs, Ds, or Fs, reported sleeping up to 25 minutes less, and going to bed 40 minutes later than their A and B student counterparts.
Sleepiness has other serious, even life-threatening reprocussions. On average, 100,000 car accidents each year are caused by drowsy driving (NSF-Drowsy Driving). Sleepiness can also cause lapses in driver alertness and attentiveness. Sleepiness is shown to increase the likelihood of substance use and abuse, including caffeine and nicotine (Carskadon 1998). Sleep Deprivation has also been shown to contribute to adolescent depression. Symptoms of Teen Depression include a change in sleep pattern and lack of energy (NSF-Teens, Sleep and Depression).
Sleepiness also contributes to social behavior problems. Sleep Deprivation leads to an awareness level, impairing the adolescents' ability to make good decisions. Ironically, sleep deprivation can also contribute to Attention Deficit Disorder and Attention Deficit Hyperactivity Disorder (NSF).
With all of the consequences of sleep deprivation, one would assume that those in charge of the American Education system would try to prevent sleep deprivation as much as possible. However, this could not be farther from the truth. In fact, school is one of the leading causes of adolescent sleep deprivation, because the early start time and heavy workload require us to defy nature's body clock. The School bells that ring as early as 7:00 a.m. in some American high schools are in significant contrast of the sleep needs of adolescents. This contrast is unhealthy and potentially dangerous. It also may be safe to say that students would perform better in school if the schedule were somehow catered to the natural body clock.
I feel that if school did not interfere with my sleep schedule, I would perform significantly better, since research shows that a lack of sleep reduces abstract thought, problem solving skills, and alertness. If the cause for these, other attention, and behavioral problems were eliminated, imagine how much better every student would do. The results would truly be phenomenal. Clearly, the best solution to the sleep schedule and education is to require public high schools to adhere to a later start time.
On 2nd April, 2006, Representative Zoe Lofgren (D-CA) introduced a congressional resolution, the "Zzz's to A's Act", to discourage earlier high school start times, so that the school schedule is more synchronized with the biological clock. "We must encourage schools to push back their start times to at least 8:30 a.m. a schedule more in tune with adolescents' biological sleep and wake patterns and more closely resembling the adult work day," she said in a meeting with Congress. The bill would accommodate administrative costs to change the school start time to after 9:00 a.m. by providing a grant of $25,000 to each school (Zoe Lofgren Home Page).
In a study by Dr. Kyla Wahlstrom, it was noted that school performance, as expected, increased when the start time of seven Minneapolis public high was pushed back from 7:15 a.m. to 8:40 a.m. Unexpectedly, other educational factors rose as well, such as school attendance. There was also a decrease in reported student depression (Wahlstrom 1999). For students who do not drive, a later start time would also mean that school would end later, closer to 5:00 p.m. If school ended at about the same time that a parent was released from his or her job, picking up children from school would become significantly easier, possibly even reducing the demand for afternoon school busing.
Like all suggestions for change, pushing back school start times would have its' consequences. Coaches worry that they would have to change morning start times or eliminate them. However, in Walhstrom's study, the high school sports teams had no change in success rate after the change in start time. In addition, a later school end time could cut into extra-curricular activities and student jobs. Students leaving school at 5:00 p.m. would have no after-school access to community functions such as libraries. However, according to the National Sleep Foundation, since "students do seem to be able to work more efficiently when they are less sleep deprived...they could therefore make better use of the time they do have."
Many people, namely parents, are against a later school start time, despite beneficial scientific research. At Nathan Hale High School in Seattle, Washington, the students gave a negative response after moving the start time from 7:45 a.m. to 8:45. They claim that a later school start time merely allows for them to stay up later, and that it interferes with after-school life. Many school administrators and professionals in the education industry are also against a later start time, simply because of the tremendous amount of work that would have to go into making a drastic schedule change. I feel that they refuse to change because they are being paid regardless of the alertness of students. In one Maryland County, the school board voted against pushing back the start time, citing reasons such as, "During the winter, elementary students would have to wait for buses in the dark." (The Baltimore Examiner) However, if they had really read the scientific reports presented to them, they would see that elementary-age children do not have the same circadian rhythm, and would not benefit from a later school start time. The campaigns have been centered only on adolescents, and changing the high school start time, not that of elementary or middle schools.
Another possible solution would be the allowance of a brief nap during the school hours. While napping would not repair the negative effects of sleep deprivation, a brief midday nap would allow students to "recharge". Napping increases alertness, and relaxes the muscles and bones that tense up during the day. Though after-meal naps have a stigma of laziness and apathy, some high schools around the World have implemented them with pleasing results. At Meizen High, in Fukuoka, Japan, the teachers turn off the lights and play relaxing music, to encourage a 15-minute nap after lunch (Washington Post). A nap during the day has very positive effects on the body, if done correctly. If a nap exceeds thirty to forty-five minutes, then the body could go through the complete REM and Non-REM cycles. Allowing the body to descend into deep sleep without getting a full night's
sleep can actually make one feel more tired after the nap than before.
Today, teenagers are buried under piles of schoolwork, on top of extra-curricular activities, not to mention work, family, and social life. There is barely time to sleep, significantly less than what the body needs, according to recent research by psychologists specializing in sleep. While I do not doubt that school is enriching our brains by teaching us about the vitals of life and knowledge, I feel that the enrichment of knowledge is shadowed by the physical harm caused to our bodies. Losing 12 vital hours of sleep per week to wake up at 6:30 every morning is hardly worth it. If teachers and administrators expect us students to perform at our highest level, then the education schedule will absolutely have to be changed in some way, and the two options aforementioned are the most logical and beneficial solutions to the paradox. While it is difficult to know if a national change in school start time would be truly beneficial, it is definitely worth a try. Even if we students do not do significantly better in school, we will at least be more rested, and much healthier.

Works Cited

Dement, William C., M.D., Ph.D., The Promise of Sleep. New York, Dell Publishing, 1999

Amy R. Wolfson, Mary A. Carskadon, "Sleep Schedules and Daytime Functioning in Adolescents." Child Development Vol. 69, No. 4 (Aug. 1998), pp. 875-877

Kubow, P., Wahlstrom, K. and Bemis, A. "Starting Time and School Life." Kappan, Vol. 80, No. 5, (1999) pp. 366-371.


Adolescent Sleep Needs and Patterns-National Sleep Foundation

Baltimore Examiner Student Pushes later start time for schools

National Sleep Foundation

Science Daily-Mouse Gene Knockout Illuminates How Light Resets Clock

Washington Post-Nation of Workaholics Sleeps on the Job

Zoe Lofgren Home Page

More about this author: Maggie Larkin

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