Scientists have a new clue about how some people are able to wake themselves up at a pre-selected time. Writing in today's Nature, a team from Luebeck University in Germany reported that such people display a buildup of the stress hormone adrenocorticotropin in their blood about an hour before the desired wake-up time. They do not yet know what triggers the buildup, however.
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Compiled by Times medical writer Thomas H. Maugh II
