The answer is : It cannot be adjusted. This is not true of the Circadian Rhythm. Circadian rhythms<span> are powerful, but people </span>can change<span> their sleep-wake cycles. He explains that </span>the<span> body's natural </span>circadian rhythms, which cycle up and down over an average 24 hours, control sleep and wakefulness and differ from person to person. I<span>t is possible for most of us to change our sleeping habits, with a little bit of planned effort. </span>
