Circadian rhythms are powerful, but people can change their sleep-wake cycles
A recent article (Jne 29th) in the Washington Post by Carolyn Butler, reports that your body's natural circadian rhythms, which cycle up and down over an average 24.1 hours, control sleep and wakefulness and differ from person to person. How much sleep you've had lately also makes a difference, influencing how great your body's drive for more shut-eye is.
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