Biorhythm is a theory that talks about human possibilities during a specific period of time during the month, based on his physical, emotional, and intellectual curves, which started from his birthday, it assumes that human possibilities can be maximized during the times of the curve's peak, and they also are minimized during his curve's bottom, the theory says that physical cycle ( curve ) takes 23 days to complete, the emotional cycle ( curve ) takes 28 days to complete, and the intellectual cycle ( curve ) takes 33 days to complete, moving endlessly from the negative to positive phases ( and the opposite ) as it restarts as soon as it finishes