Stress causes the greatest negative impact on overall GPA, according to the American College Health Assessment (ACHA) ranking of obstacles to learning. It is the compounding of multiple stress areas that seems to have the greatest impact. Stress experienced from new living situations, relationship changes, loss of friends or family, or debt affects academic performance. A student's inability to deal with multiple stressors manifests in the body as fatigue, headaches, depression and anxiety, which can result in substance abuse and sleep and food disorders that lead to illness, poor class attendance and academic self-destruction, according to the ACHA.
The relationship between health and GPA was studied at Loyola University, New Orleans. Healthy lifestyle criteria were based on smoking, alcohol, sleep, exercise and diet habits. The students observed, ages 18 to 22, proved that those who committed to a healthy lifestyle did not show an increase in GPA, although students who avoided fast foods did achieve a higher GPA. A 2001 study on sleep by Kelly, Kelly and Clanton revealed that GPA is related to the number of hours a student sleeps each night. Students sleeping more than nine hours per night achieved a higher GPA than those who slept seven to eight hours per night.
The controllable habits of tobacco and alcohol have been found to negatively influence GPA level. In 2001 the American Heart Association concluded that academic performance is impaired when a student smokes more than 20 cigarettes per day because smoking reduces the oxygen supply to the brain, which compromises brain function and in turn limits one's ability to learn. Additionally, cigarette cravings create distractions from study and reduce in-class focus, resulting in retention deficits. Second to nicotine addiction, alcohol has been shown to impair attention and affect memory function, causing further stress on the student and negatively affecting GPA.
According to the 2003 National College Health Assessment study on student GPA, undesirable life-changing events resulted in lower grades more than the regular stresses of everyday college life. Life changes such as the severing of personal relationships, relocation, death of a family member, changes in social status, issues relating to credit debt and the lack of health insurance greatly impact the student's stress level, which is ultimately reflected in overall health and the ability to retain academic stature.