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September 21-October 4, 2001 |
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If you choose to follow any links to the abstracts and/or complete text of articles, books, and documents listed below, you will be leaving the Strategian Web site. If you wish to return to this page from the Web page you are sent to, please use the Back option of your browser. Feature Items: Todd S. Horowitz, Brian E. Cade, Jeremy M. Wolfe, and Charles A. Czeisler Efficacy of Bright Light and Sleep/Darkness Scheduling in Alleviating Circadian Maladaptation to Night Work. (... it is now well established that sleep, alertness, and cognitive functioning are determined by the interaction of two processes [in the human body], the endogenous circadian pacemaker and a sleep homeostat. The circadian pacemaker, located in the brain, generates an endogenous [occurring inside the body], near-24-h[our] rhythm that regulates subjective alertness, sleep propensity, and a wide variety of cognitive functions, as well as core body temperature and melatonin secretion. The pacemaker is thought to be highly affected by light which may be the principal factor which keeps the pacemaker and its 24-hour rhythm synchronized [happening on a regular schedule]. The homeostat mediates a continual decline in performance and corresponding increase in sleepiness with time elapsed since awakening. Individuals who work at night or otherwise attempt to change the usual 24-hour rhythm of their bodies suffer because the timing of their sleep/wake and work schedule remains permanently out of phase with the timing of environmental light. As a result, individuals who work at night often experience various health-related problems such as gastrointestinal difficulties, cardiovascular disease, and trouble sleeping during the day. In addition, compared to individuals who work during the daylight hours, people who work at night may not be as alert or think as clearly and quickly leading to the possibility of an increase in job-related and/or vehicle accidents and reduced work performance. The authors studied twenty-seven men and 27 women aged 20-40 and manipulated the amount of light they were exposed to while working [bright light versus regular room light] and their sleep schedules [with some subjects, the researchers attempted to eliminate as much internal and external light as possible while sleep or rest was occurring]. The subjects underwent an experiment lasting several days that attempted to simulate the change from a schedule of working during the day to working during the night. The authors conclude by stating that exposure to bright light while working at night, a consistent sleep/wake schedule, and keeping out as much light as possible while sleeping can work together to achieve a reliable treatment for circadian maladaptation to night work and avoid the health, sleep, and other problems often experienced by individuals who work at night. The authors do mention one caveat for their results--the subjects in this study were not allowed to use and were screened for the use of drugs such as alcohol, nicotine, and caffeine, as well as over-the-counter sleep medications. Drug use of this nature is quite common among shift workers, and all of these agents can affect sleep quality, and there is some evidence that alcohol and nicotine can directly alter circadian rhythms. Other keywords and phrases -- diurnal, phase misalignment, phase shifts, sleep deprivation, sleep in darkness, sleep research -- from the text of the article; please see the bibliography) American Journal of Physiology - Endocrinology and Metabolism Volume 281, Number 2 (August 2001): E384-E391. How to find the above journals, magazines, and other publications? See Step 3: Locate of the Information Strategy for details. Questions about any or all of the above? Please let me know. |
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