Circadian Rhythms - Essay Example

Introduction to Psychology 25 November 2009 Circadian Rhythms Sleep is the of consciousness experienced as a part of 24-hour life cycle bringing about comfort and relaxation from the days hard work. Sleep can be divided into rapid eye movement (REM) and non-rapid eye movement (NREM) that regulate the maintenance of sleep-wake cycle which is the most important bodily rhythm. There are various bodily rhythms categorized mainly into biological or physiological rhythms and psychological rhythms which have major impact on human behavior. The biological or physiological rhythms are controlled by internal biological clocks including (1) Annual cycles: Humans experiencing certain seasonal variations possess mood alterations especially during winter. (2) Twenty-eight days cycles: Female menstrual cycle averaging about 28 days believed to cause mood fluctuations in some. (3) Twenty-four hour cycles: Humans experience various variations in body temperature and hormonal secretions on a 24-hour cycle. (4) Ninety-minute cycles: Variations during various stages of sleep (David G. Myers, 269). Circadian rhythms are the regular changes in biological processes that follow rhythmical patterns over a 24-hour period (Theo Sonderegger, 55). Humans tend to respond to every 24 hour spin of earth on its axis scheduling the tasks and needs according to environment spending about 8 hours in sleep and are awake for 16 hours within the 24-hour circadian cycle. The mental and physical functions are active during the wakeful state while sleeping state there is decrease in body temperature, blood pressure, and heart rate. Circadian rhythm takes place in wide variety of organisms apart from humans and are controlled by environmental and internal factors. Temperature and light are the common environmental factors. The circadian cycle is controlled by suprachiasmatic nucleus (SCN) located in hypothalamus region of brain that influences the sleep-wake cycle by receiving signals from retina of eye about light and dark. The photoreceptor cells in retina transmit signals on light activation and deactivation via neurons of retinohypothalamic tract to the SCN, which are further transmitted to pineal gland via the superior cervical ganglion. The superior cervical ganglion releases noradrenaline into pineal cells during dark, which is followed by transformation of serotonin into melatonin. (Michael W. Eysenck, 112). The SCN leads to the release of more melatonin hormone from pineal gland when the light levels are low that in-turn influences the brainstem mechanisms, thus regulating the sleep. Any shift in the circadian cycle requires certain time to reset the internal clock; these changes vary from person to person. Travelling across different time zones cause circadian rhythm stress or jet lag. These shifts in the circadian rhythm cause serious issues with sleep-wake regulation mismatching the demands of life, thus manifesting circadian rhythm disorder. These mismatches can be caused due to external factors like jet lag or from lack of environmental time cues, as in blind people (Carlos Schenck, 73). There are numerous health problems associated with the shift of circadian rhythms like advanced sleep phase disorder (ASPD), delayed sleep phase syndrome (DSPS), free-running disorder (FRD) and irregular sleep-wake rhythm (ISWD). Free-running or non-entrained circadian rhythm disorder means that the internal clock is not programmed to a normal cycle of about 24 hours but is much longer or shorter instead (Carlos Schenck, 71). Humans with this disorder do not follow regular sleep patterns and have free-running type shifts moving later and later everyday. It is commonly observed in blind people who lack light cues to reset the clock of brain as light plays vital role in resetting the sleep-wake clock to 24-hour schedule, without which people drift their sleep patterns. The idea of everyone needs eight hours of sleep is not true, newborns spend most of time per day sleeping and so do some adults. Some people suffice with less than 7 hours of sleep while others prefer more than 8 hours, these sleep patterns depend on various factors like age and can affect a person to greater extent. On an average humans sleep for at least 7-8 hours to make them refreshed and efficient to perform more accurate work than those individuals who lack proper sleep. Sleep deprivation creates sleep debt that needs to be repaid the next day. These sleep deprivations can cause depression, memory problem, decrease of immune system, reduced performance and alertness etc. instantly while some of the long term issues are mainly related to medical illnesses like high blood pressure, heart problems, obesity, injuries from accidents, fetal growth retardation especially when mother doesn’t get proper sleep during the first trimester, mental impairment, psychiatric issues like depression, memory decrease and loss of concentration etc. Hence, every individual does require a minimum of 7-8 hours of sleep to regain their strength and improve the brain functioning. A good night sleep leaves the person refreshed and restored to perform the next day’s tasks. Normal sleep patterns are influenced by various factors like age, culture, gender, body mass, individuality, genetics and physical activity. Certain internal and external factors interrupt the normal sleep pattern. The external factors are: 1) Noise: Some people find it difficult to sleep in presence of minor noises while some might fall asleep but tend to wake up with any noises in surroundings. 2) Light: Most individuals prefer dark room to have a proper night sleep and small beam of light would also disrupt normal sleep. 3) Temperature: Changes in the temperature would not just cause difficulty in falling asleep but also wakes the person who is fast asleep. The internal factors are: 1) Diet: Sleep is affected by the kind of food we intake, more caffeine containing beverages causes difficulty to sleep and leaves person restless. 2) Pain: Body pains mild or major would interrupt the sleep and leaves person awake until the pain subsides. 3) Drugs or Medicines: Any kind of prescribed or over the counter medications do affect sleep in 3 ways: (a) causing sleep by intent (b) cause drowsiness (c) causing insomnia or other sleep disturbances by side effect. 4) Exercise: Physical exercise promotes sleep as the person is stressed enough but overly exercising would leave person with body pains disrupting his sleep. Some of the lifestyle changes can also interfere with normal sleep patterns like relocation, loss of spouse, having roommate, retirement etc. Thus affecting the amount of time a person is asleep or awake. References 1) David G. Myers, “Psychology”, 2004, < http://books.google.com/books?id=vclxT07s59sC> 2) Michael W. Eysenck, “Psychology: An International Perspective”, 2004, < http://books.google.com/books?id=l8j_z5-qZfAC> 3) Theo Sonderegger, “Psychology”, 1998 < http://books.google.com/books?id=zTWcpiUlST0C&dq=psychology> 4) Carlos Schenck, “Sleep: The Mysteries, the Problems, and the Solutions”, 2007, < http://books.google.com/books?id=gZZ91H3uG04C> 5) Dennis Coon, John O. Mitterer, “Introduction to Psychology: Gateways to Mind and Behavior” 2008, < http://books.google.com/books?id=vw20LEaJe10C> 6) WebMD Better information. Better health. < http://www.webmd.com/sleep-disorders/guide/understanding-sleep-problems-basics>, 7) Sue Meiner, Annette Giesler Lueckenotte, “Gerontologic nursing”, 2006, < http://books.google.com/books?id=ex92-LQPRfsC> 8) Christine Brooker, Maggie Nicol, “Nursing adults: The practice of caring”, 2003, < http://books.google.com/books?id=ao1R9sOIQZQC> 9) Sharon L. Schutte-Rodin, MD, “SleepEducations.com”, March 27, 2006 < http://www.sleepeducation.com/Disorder.aspx?id=59> 10) Encyclopedia Britannica, < http://www.britannica.com/EBchecked/topic/118220/circadian-rhythm#> Read More