circadian rhythms
...Live feed-type entertainment such as radio or television is not allowed. In addition to a lack of freedom and information, the subjects are tested quite often. For example, take the case of one such study at the Laboratory of Human Chronophysiology at Montefiore Hospital. In the study, subjects had small blood samples taken every twenty minutes, alertness tests about every hour, brainwave monitoring of any sleep, and continuous rectal temperature readings (Coleman 7). Subjects of any such research have to be crazy enough to willingly go through this kind of testing but sane enough to call normal. The experience was described by Preston Keogh, a subject, in his journal. “Sometimes I felt like a prisoner, trading my youth for money. Although I didn’t feel crazy, I thought others might think I was… They took blood samples every fifteen minutes. I had a catheter in my arm, and a butt probe and all these things were attached to a movable pole. The first few days there was a definite presence but after the first week it became a part of you. It was like having a tail.” Finding people who are willing to live in these conditions is a major obstacle to research. It could be asked, “If it’s so hard to do, why bother with all this research? What’s so important about sleep patterns?” The importance of sleep pattern research is threefold. Not only will research in the field of circadian rhythms help us maximize the alert hours of the general population, but it will also help to better maximize the schedules of shiftworkers. Shiftworkers are laborers, usually factory based, that run on a continuous 24 hour schedule, never stopping. The idea of shiftwork is that expensive or crucial machinery can be kept operating 24 hours a day. For example, a telephone operator or a nurse would work on a 24 hour shift system. Sleep pattern research with also help set the schedules of people in situations where the time-giving cues of light are not available, such as in spacecraft or submarines. To be able to get shiftworkers or submarine crews to work more efficiently might mean that less people and equipment may be needed, possibly saving hundred of thousands of dollars. The first step in this research is defining a normal sleep pattern. Research has defined a “normal” sleep pattern for adults. Studies have been done all over the world in the field to describe what is considered normal among adults. In one such study sponsored by Stanford University, three rooms of a hospital were sectioned off for testing. The center room was used as a control room, and the other two rooms were used as bedrooms for test subjects. The test subjects were instructed to stay in the rooms, which had no windows or clocks, and sleep on a regimented schedule for twenty days. After the twenty days passed, they were told to sleep whenever they wanted to. The scientists asked that they take only one sleep period a day. Volunteers had no contact with the outside world other than the staff. The staff, of course, was instructed to remove any trace of a sense of time from their habits. They had to remove all wristwatches, use time-neutral phrases like “hello” instead of “good morning,” and shave just before handling test subjects. Their work schedules were determined randomly by computer. Even with all of these precautions, the test subjects mostly followed identical patterns of sleep. These somewhat identical sleep patterns were therefore dubbed “normal” and taken as natural (Coleman 6). Normal sleep patterns include a few main ideas. First, most adults sleep for about eight hours each day. If asked to sleep less, most can function at the same level of efficiency with less sleep. In fact, after eight weeks of sleeping for five and a half hours a night, most subjects report that they no longer felt drowsy during the day. However, these sleep deprivation studies have shown that even after months of sleeping four or five hours a night, people go back to the eight hour standard citing that they just feel better when they get more sleep (Coleman 98). In addition to an eight hour sleep period, normal sleep patterns include free running. Free running is the practice of going to sleep one hour later than the night before. In the aforementioned Stanford study, most subjects were found to fall asleep an hour after they would have the night before. Scientists believe that this phenomenon, called free running, is due to a natural 25 hour cycle that humans run on. In the absense of time cues, 25 hours seems to be the preferred length of day for the average adult (Coleman 8). Beyond the 25 hour cycle, scientists know bits and pieces of other information. For example, scientists know a small amount about alertness levels. Alertness levels are highest during the middle of the day, and lowest during the first hour before and after sleep. After a sleepless night, a normal person will return to higher alertness on the cue of light. So, if a person were to stay up all night intentionally, they would feel somewhat refreshed in the morning, even without sleep. This feeling, of course, lessens over repetition, so sleep cannot be abandoned altogether. Now that scientists know some of the basics of normal sleep patterns, the next step in research is correlating between time cues and those sleep patterns (Coleman 20). Currently, research shows several correlations between certain time cues and circadian rhythms. One such time cue is light. For example, people in subarctic climates often have very long or very short days. During winter it can stay dark for all 24 hours of the day. As a result, some people suffer from SAD, or Seasonal Affective Disorder. Those with SAD have symptoms of depression, increased weight, and, perhaps most importantly, sleepiness. According to Richard Coleman, the disorder is related to the secretion of melatonin, a hormone that is released from the pineal gland during the night. The body senses that it is dark, and then responds by secreting melatonin. Those with the disorder actually suffer from an overdose of melatonin due to the lack of daylight. By not getting enough sunlight, their bodies over-secrete melatonin, causing the symptoms above. By having the patient sit in front of a light for three to five hours, doctors have reduced the amount of depression and sleepiness in many cases by simulating a 13 hour light cycle. This 13 hour light cycle is very similar to the light cycle of those found in warmer climates, and is much more beneficial to those with SAD. It may seem odd that the body could unconsciously identify the availability of light, deciding when to be alert and when not to be based on the presence of light or lack thereof. However, such light-sensing can be physiologically explained. Last April, Dutch and Japanese scientists studied mice without normal rods and cones in their eyes. Rods and cones are the light and color sensing structures of the retina that allow animals the ...