A study, reported recently in Current Biology, examined why adolescents go to bed later. Researchers in Germany asked 25,000 individuals (from 8 to 90 years of age) about their sleep and wake times. Based on the participants'responses, the researchers mapped their "chronotypes" (an individual's endogenous or natural circadian clock "synchronises"or alignments to the 24-hour day).
The results of the study indicated that children are early chronotypes and become progressively later during development, reaching a maximum lateness around age 20, when they become earlier again. A comparison of men and women showed that women reached their maximum lateness earlier (19.5, compared with 20.9 years in men). The results further suggested that women mature faster than men.
One study linked multiple pregnancies to an increased risk of developing atrial fibrillation later in life, and another investigated the association between premature delivery and cardiovascular disease.
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