Statistics regression anaylsis, Ho and null hypothesis

How do I determine sleep affect on GPA or is something else affecting grades as much, using statistics?

Background
There have been various studies that say students' grades are affected by poor diet, high amounts of stress, lack of sleep, and excessive alcohol use. Perhaps one of the most important factors out of those mentioned is the overwhelming number of students who are not getting enough sleep.
Lack of sleep can also lead to difficulty in studying, concentration, performance, and physical ailments such as; fatigue and irritability. Researchers have identified three main classifications of sleepers, the first short sleepers are those who sleep 6 or fewer hours nightly. The second classification includes those who get 7 to 8 hours of sleep nightly. Lastly are the long sleepers who sleep 9 or more hours per night (Kelly, W., Kelly, K., & Clanton, R. 2001).
An article recently published in the Journal of American College Health describes recent studies in regards to the factors mentioned above. Based on the studies conducted throughout this article, researchers have found that college age students are more susceptible to stress related disorders. Researchers conducted a very in depth survey to find that college students are often times presented with sleep disorders, depression, eating disorders, and feelings of exhaustion. One of the primary areas of concern for researchers was the amount of sleep that the volunteers had nightly, on average, and its relation to their performance in their respective courses. This study also found that lack of sleep correlates directly to whether or not an individual college student is more susceptible to depression. The study highlights how this can occur. Firstly, a student that does not get adequate amounts of sleep at night is not likely to perform well in his or her classes. Thus, such individuals are presented with an added degree of stress. This addition of stress into the equation leads to the individual being overcome with thoughts of helplessness which creates the feelings of depression that have become so prevalent amongst college students as of late. The study conducted found that only 5.3% of participants (out of 227) stated that received 6 to 7 days of quality sleep per week. Additionally, the study found that 19.4% stated that they felt well rested 0 to 1 days per week. The study has pointed to sleep problems as being one of the â??top 3 impediments to academic achievement on college campuses (Armstrong, S 2007).â?
It was found that students who were â??evening typesâ? showed greater declines in GPA when transitioning from high school to college. These individuals were also found to have a significantly lower GPA compared to those students who were considered â??morning typesâ?. The average GPAâ??s showed that â??evening typesâ? on average achieved about a 2.84 and â??morning typesâ? a 3.18 (American Academy of Sleep 2011). The study surveyed thirty four students as they began their freshman year in college and then again in their senior year. They were able to find that students that were able to change their sleep cycles and become more â??morning typesâ? showed greater improvement in their GPAâ??s over the course of their college career.
An article recently published on CollegeThrive.com suggests that students make time for naps throughout the day to allow the brain to recharge. This in turn allows for individuals to be more productive in their studies and alleviates some of the sleep deficit. Some other ideas to improve performance are to eat breakfast daily and sleep through the night, meaning at least 7 hours. In addition, students are encouraged to drink lots of water and try to stay away from too much caffeine as this also inhibits sleep. By taking some of these considerations into mind students will find that they are more productive and feel more energized throughout the day.