The light appear to interfere with the bodys ability to create this hormone which is responsible for sleep and wake cycles

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.

Ithink the answer is talking about their problems  

This needs more info

What are the options?