Effects of Circadian Rhythm - Lab Report Example

Effects of Circadian Rhythm Abstract There are many defining factors to circadian rhythm. It can be affected by age, gender ,the hours worked and hormone levels. When the circadian rhythm is not working well, it causes a problem with sleep patterns, sometimes for long periods of time. The goal of this lab was to determine what affects the circadian rhythm has on "morning people" and "evening people" of different ages and genders. The method for study was conducted using students enrolled in PSY 3350, Biological Psychology to interview 21 morning people and 22 evening people. The age range chosen was ages 8 to 59. Word lists were used and a five minute memory test in which the participants had to write down all the words they could remember. The participants were then given reading to distract them and they went back to write down the words they remembered again later. The testing was done at 9 am in the morning and at 9 pm in the evening. These times gave us representations of the responses from "morning" people and "evening " people. Outcomes told us that for morning people there was not a lot of difference but in the case of evening people, there was a lot of difference. Introduction Sleep and wakefulness occur in a cyclic manner and is integrated into the twenty four hour light dark cycle in a day. The circadian time system is to provide an organization in the brain that allows the physiology of the body to process both physiology and behaviors therefore allowing effective adaptation of the environment (Porth, 2007). At the behavioral level there is expression of regular cycles of sleep and waking which affects the bodies functions such as temperature and hormone secretion. Daily rhythm of the sleep wake cycle is part of a time keeping system created by an internal pacemaker or clock. People placed in a dark room with no clock cues showed a cycle length of in general 23.5 to 26.5 hours. Since the normal time seems to be greater than 24 hours, a daily resetting of the clock is necessary to synchronize with the environmental day. Circadian rhythm disorders are usually a disruption of a person's SCN or suprchiasmatic nucleus which causes the internal clock to change. . This clock for circadian rhythm lies in the SCN or suprachiasmatic nucleus. The nucleus is important in determining sleep patterns. Rhythm disorders can be caused by many factors, including, shift work, pregnancy, time zone changes or jet lag, medications changes in routine, and illness as well as age.(Vardar, 2008). How the circadian rhythm is functioning or not functioning can determine whether a person is able to function or not. That clock has everything to do with how the day goes and may very well affect how efficient and successful the person is. This paper will discuss this information in relation to the study done for class and relate the theory back to "am people" and "pm people" and what that really means. Methodology The aim of the study was to determine whether there was a change in the circadian rhythm based on age and work style. This was a cross sectional study. The thesis related to the fact that there are some people who do better in the morning and some who do better in the evening. The hypothesis done by the two tales test was the belief that morning people do everything best in the morning and evening people do everything best in the evening. The study looked at age differences, as well as REM sleep and temperature rhythms. The average age of the persons in the study was 30 years old with the youngest being 8. This was a standard blind study in which standard deviation was calculated on total scores and n. Results The Mayo Clinic defines healthy sleep as "an adequate amount of sleep that produces daytime alertness and a feeling of well-being. You should not need an alarm clock to waken when you are getting enough sleep (Humphries, 2009)". This becomes more and more clear as we look at the results of this study and compare to others. The mean age was 36 years old for morning people and 30 years old for evening people. The overall average age was over 30. The scores were as follows: In the morning, the morning people had a mean score of 15.24 and a standard deviation of 4.25 and the evening people had a mean score of 14.68 and a standard deviation of 4.15 which shows that morning people, in fact do function better in the morning than evening people but the difference is not as great as would have been expected. In the evening the morning people scored 14.38 with a standard deviation of 3.97 and the evening people had a mean score of 16.5 with a standard deviation of 3.74 as you will note in the chart below: Descriptive Statistics Table 1 Mean Difference Scores for Mental Performance of Morning Types and Evening Types Mental Performance Morning Evening M SD M SD Morning Typesa 15.24 4.25 14.38 3.97 Evening Typesb 14.68 4.15 16.50 3.74 Note. an = 21 for morning types, bn = 22 for evening types. Morning t(20) = 1.40, p > .05 Evening t(21) = -2.57, p < .05 Mean age – 36 years for morning people Mean age = 30 years for evening people This is more significant as not only are evening peoples scores higher in the evening but they also have a lower standard deviation which means that this is true of more of them. This compares to Varder's study which studied 30 evening types and 34 morning types of varying ages. No specific gender was chosen. Scores for evening types were much higher than those of morning types in almost the same ratios. Discussion All organisms are affected by circadian rhythm or the rhythm of light and dark, level of physical activity, and ambient temperature change (Vardar, 2008). Individual preferences of a person's daily lifestyle and sleep-wake timing reflects inter-individual variation. Evening types are able to sleep late in the mornings and they are more alert at night. On the other hand, morning type individuals get up early and are more alert n the morning than in the evening. Evening type people wake up and begin sleep later than morning types do. Morning types are also more rigid in their need for their circadian rhythm to work than those that are evening type. Most of us fit somewhere in the middle. Studies show that people who are evening type people have a tendency to have more emotional problems, life habits that are irregular and have more sleep issues(Vardar, 2008) Normal work schedules seem to fit the morning types lifestyle rather than the evening type. That does not mean that a lot of those same people may have to work hours that do not fit their type. Tang managed a retrospective study of 124 non-demented elderly people (age 65-88.5) who complained of sleep disturbances (Tang, 2007). The assessment that was done included changes in the sleep homeostat: total sleep time (TST), insomnia, snoring, apnea-hypopnea, sleep efficiency and probability based evaluation of sleep variables(Tang, 2007). He found that to further the problems already discussed, there is the issue of waking up after sleep onset. The increase according to Tang (2007) of sleep onset latency in the elderly may increase daytime sleepiness which then decreases slow wave sleep and rapid eye movement or REM. The total sleep time that was noted showed great variable in what seemed to be the sleep time that each individual needed. For instance, the extra long sleeper needed 8.5 hours and the extra short sleeper needed less than 5.5 hours. All two tailed P values here were .05. which was considered significant, which was the case in our study. There were however, other interesting things that made a difference. BMI affected sleep. Those that had the highest BMI sleep the longest and had the longest duration of snoring. Hypertension affected sleep. Patients who had the highest blood pressure also slept the longest. This author made the decision by the end of his study that the largest prevailing factor was the affect of the SCN, again very familiar to our study results. Melatonin secretion may be one of the many issues that elderly patients have other than sleep apnea which affects more than would be though. The study has to lead to the need to better determine the answers as a circadian rhythm that is not in effect working well for the elderly can signal disaster in a fall or more based on the lack of reasonable sleep. Nursing is one of the professions that consistently have difficulty with sleep loss based on job status. Irregular work schedules put nurses at risk for sleep disruption as they attempt to sleep in the daytime. There are many studies that show that nurses are at risk for many health issues as well as patients safety issues based on their sleep issues. This paper will use nursing as the example of issues with job shifts since there is presently so much being studied here, at present. Nurses have a great deal of sleep loss. Still today, there are a great deal of female nurses, although this is changing and there are more and more males in the mix. The average nurse sleeps 7.5 hours or less. Over time as sleep deficiency accumulates for these nurses, it has been shown that they are less alert, their neurobehavioral performance is not as good, their endocrine function and physical and emotional well being suffer. Six or fewer hours of sleep show a deficiency in critical thinking skills and task performance skills (Humphries, 2009). Most nursing shifts today are 12 hour shifts. Studies show that the risk of errors and near errors are increased when these nurses do overtime or work past their 12 hour shift. Humphries (2009), also tells us that there is a decrease in growth hormone, decrease in immune protective cells, increase in cortisol levels and impaired glucose tolerance levels. The release of leptin and gherline hormonesis altered so hunger cycles are also affected. It has already been shown that decreased sleep causes an increase in BMI. The risk of high blood pressure increases with 6 or fewer hours sleep. Moodiness and emotional lability occur with sleep loss (Humphries, 2009). Memory is another one of the major issues we find affected by the amount of sleep that we get. The SCN provides us with a sleep-wake cycle, we have seen that. It is found in some studies now, that the circadian system is critical to the ability to memorize things. If a circadian system is taken away somehow, like some of the people who have been placed in totally black rooms, they may not remember much. It appears that GABA which is a neurochemical is blocked. Learning requires that the GABA be functioning to supply our memories. This may be part of the answer for age related memory loss. As humans age, the circadian rhythm begins to break down. This requires more study to understand whether there is something that can be done to change this with ageing and whether it may very well affect dementia and Alzheimers. There are some gender issues and Chung discusses those in her study (2009). Women are now about half of the work force and because of the reproductive system, women are more affected by changes in circadian rhythm, especially those that are shift related (Chung, Wolf, & Shapiro, 2009). The change in shift work can have a negative impact in hormone producation in women which not only allow for reproduction but affect the stabilization of other issues in their bodies. In all of the studies noted by Chung, women who had disturbances in shift work had poorer sleep than men, difficulty staying asleep, difficulty returning to sleep and twice as many take medications to sleep. 40% of women on shift work complained of significant problems sleeping and 30% complained of reproductive issues. Conclusion The lab study performed and the other studies noted throughout this paper compare well as far as outcomes. Humm compares everyone to the owl and the lark. In this lab it is easy to see why Humm used those terms as there was definitely a difference in how daytime and nighttime people responded. It has been know for quite some time that some people did things well in the day and other in the night. Until recently, that was just that was just taken for granted. Now we look to the circadian rhythm to figure that out and like our lab data, prove that this is not a suspicion but is true. The SCN has, according to all of the studies that were reviewed for this paper, has a tremendous effect on health. Sleep definitely affects the ability to become and stay healthy References Chung, S., Wolf, T., Shapiro, C. (2009). Sleep and health consequences of shift work in women. Journal of Women's Health. 18(7). DOI: 10.1089/jwh.2007.0742. Humphries, J. (2009). Workplace debt: Sleep loss. Creative Nursing. 15(1). 23-48. Humm, C., (2009). Workers' wake-up call. Nursing Standards. 24(4). 22-40. Medical Pharmacies, (2009). 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