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POPSCan You Catch Up on Lost Sleep? The good news is that, like all debt, with some work, sleep debt can be repaid—though it won't happen in one extended snooze marathon. Tacking on an extra hour or two of sleep a night is the way to catch up. For the chronically sleep deprived, take it easy for a few months to get back into a natural sleep pattern, says Lawrence J. Epstein, medical director of the Harvard-affiliated Sleep HealthCenters. Go to bed when you are tired, and allow your body to wake you in the morning (no alarm clock allowed). You may find yourself catatonic in the beginning of the recovery cycle: Expect to bank upward of ten hours shut-eye per night. As the days pass, however, the amount of time sleeping will gradually decrease.
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POPSHumanity Was Genetically Divided For 100,000 Years the study provides insight into the early demographic history of human populations before they moved out of Africa. “These early human populations were small and isolated from each other for many tens of thousands of years,” says Rosset. MtDNA, inherited down the maternal line, was used in 1987 to discover the age of the famous “Mitochondrial Eve,” the most recent common female ancestor of everyone alive today. This work has since been extended to show unequivocally that “Mitochondrial Eve” was an African woman who lived sometime during the past 200,000 years.