Circadian rhythm phase shifts and endogenous free-running circadian period differ between African-Americans and European-Americans.

ABSTRACT: Successful adaptation to modern civilization requires the internal circadian clock to make large phase shifts in response to circumstances (e.g., jet travel and shift work) that were not encountered during most of our evolution. We found that the magnitude and direction of the circadian clock's phase shift after the light/dark and sleep/wake/meal schedule was phase-advanced (made earlier) by 9 hours differed in European-Americans compared to African-Americans. European-Americans had larger phase shifts, but were more likely to phase-delay after the 9-hour advance (to phase shift in the wrong direction). The magnitude and direction of the phase shift was related to the free-running circadian period, and European-Americans had a longer circadian period than African-Americans. Circadian perio

SUBMITTER: Eastman CI 

PROVIDER: S-EPMC4323653 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature