Shift work includes any work that differs from a steady 9 am to 5 pm schedule (1). Many studies implicate shift work’s adverse effects on poor health outcomes. For example, increased risk for obesity, diabetes, and cardiovascular disease are associated with shift work (2-5). When the sleep/wake cycle is properly aligned with the endogenous circadian clock, the circadian clock “optimally regulates our physiology and behavior across the 24-hour day” (6). However, previous research finds that the unusual hours for shift work disrupts the circadian clock (7, 8), and results in “chronic misalignment between the endogenous circadian timing system and the behavioral cycles, [such as] sleep/wake and fasting/feeding cycle” (6). The physiological maladaptation to misalignment of the circadian clock and behavioral cycles may be the fundamental mechanism that causes poor health outcomes in shift workers (9, 10). Therefore, understanding these maladaptive mechanisms may reveal potential areas of intervention to improve the health prognosis of
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induces circadian clock and behavioral cycle misalignment in order to evaluate metabolic, autonomic, and endocrine function. The study population consisted of 10 adult subjects, 5 of which are female. A comprehensive medical examination was conducted prior to the study to ensure the subjects were healthy with no significant medical conditions. The investigators first established a stable baseline of circadian phase angle entrainment by having subjects “maintain a regular sleep-wake schedule for 2 weeks” (6). Once a stable circadian phase angle of entrainment was established, subjects were placed in a laboratory suite that excluded environmental time cues. During 10-day laboratory protocol, the first two day and nights were used to establish a baseline with 8 hours of sleep. Following the baseline days, subjects experienced 7 recurring 28 hour sleep-wake
induces circadian clock and behavioral cycle misalignment in order to evaluate metabolic, autonomic, and endocrine function. The study population consisted of 10 adult subjects, 5 of which are female. A comprehensive medical examination was conducted prior to the study to ensure the subjects were healthy with no significant medical conditions. The investigators first established a stable baseline of circadian phase angle entrainment by having subjects “maintain a regular sleep-wake schedule for 2 weeks” (6). Once a stable circadian phase angle of entrainment was established, subjects were placed in a laboratory suite that excluded environmental time cues. During 10-day laboratory protocol, the first two day and nights were used to establish a baseline with 8 hours of sleep. Following the baseline days, subjects experienced 7 recurring 28 hour sleep-wake