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Abnormal Sleep Schedule Linked to Adverse Effects

Lab study with 28-hour day linked to altered leptin, glucose, cortisol rhythm other changes

WEDNESDAY, Mar. 4 (HealthDay News) -- An altered sleep-wake cycle such as that seen during jet lag and shift work can have wide-ranging metabolic and cardiovascular implications, according to research published online Mar. 2 in the Proceedings of the National Academy of Sciences.

Frank A.J.L. Scheer, Ph.D., of Brigham and Women's Hospital in Boston, and colleagues analyzed data from 10 healthy men and women aged 19 to 41 who underwent a 10-day laboratory study in which they lived in individual suites and ate and slept according to a 28-hour "day" without time cues. They ate four meals of equal calories during each day.

When subjects' eating and sleeping times were misaligned from normal, leptin was 17 percent lower, glucose and insulin were 6 and 22 percent higher, respectively, mean arterial pressure was 3 percent higher, sleep efficiency was reduced by 20 percent, and the daily cortisol rhythm was completely reversed, the researchers report.

"Approximately 8.6 million Americans perform shift work, which is associated with increased risk of obesity, diabetes and cardiovascular disease," the authors write. The effects of the circadian misalignment on glucose, leptin, sleep efficiency and other factors "may provide a mechanism underlying the increased risk for obesity, hypertension and diabetes in shift workers."

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