Human sleep/awake cycles at three different developmental stages are illustrated in the graphs below. The parts of the graph that lie above the horizontal axis represent times when the person is awake, while those parts below the axis represent times when the person is asleep.
copy/paste into browser
http://www.flickr.com/photos/40395848@N04/3714188579/

a. Describe the period for one graph. Explain your reasoning. Use the appropriate units.
b. Which of these graphs appears to be the closest to a simple harmonic function? Explain your reasoning.

Question

Human sleep/awake cycles at three different developmental stages are illustrated in the graphs below. The parts of the graph that lie above the horizontal axis represent times when the person is awake, while those parts below the axis represent times when the person is asleep.
 copy/paste into browser
 http://www.flickr.com/photos/40395848@N04/3714188579/ 

a. Describe the period for one graph. Explain your reasoning. Use the appropriate units. 
b. Which of these graphs appears to be the closest to a simple harmonic function? Explain your reasoning.