This isn't possible except you have a system where there isn't competition and the survival of the fittest in the aspect of the food chain
Answer:
Questions need to have independent variable and dependent variable.
independent variable in this case would be :
phone usage
classical music
counting sheep
dependent variable in this case would be :
hours of sleep
So ask questions like
Will phone usage decrease the hours of sleep students get each night?
Will listening to classical music increase the hours of sleep students get each night?
Will counting sheep increase the hours of sleep students get each night?