Aplanet rotating causes cycles of day and night on that planet, and our bodies and senses adjust to the cycle of day and night so that we may work in the day and sleep at night. Given these facts, sleeping at night and working during the day is determined by what thing happening among the following options:
- clouds forming
 - planet rotating
 - heat energy
 - dehydration
 - solar flares
 - animal reproduction
 - Animal survival
 - sweating


 

  planet rotating       