Here are some key points in the typical 24-hour cycle: 6 A.M. Cortisol levels increase to wake you up 7 A.M. Melatonin production stops 9 A.M. Sex hormone production peaks 10 A.M. Mental alertness levels peak 2:30 P.M. Best motor coordination 3:30 P.M. Fastest reaction time 5 P.M. Greatest cardiovascular efficiency and muscle strength 7 P.M. Highest blood pressure and body temperature 9 P.M. Melatonin production begins to prepare the body for sleep 10 P.M. Bowel movements suppressed as the body quiets down 2 A.M. Deepest sleep 4 A.M. Lowest body temperature
