In this study, the relationship between mental endurance and physical activity levels of BESYO students and sleep quality was investigated. The relational survey model, which is one of the quantitative research methods, was used. As data collection tools, Sports Mental Endurance Inventory, International Physical Activity Questionnaire, Pittsburgh sleep quality index (PUKI) and demographic form prepared by the researcher were used. According to the data obtained, there is a very weak positive correlation between the Mental Endurance Inventory in Sports and Total Physical Activity. There is a very weak negative relationship between the Mental Endurance Inventory in Sports and PUKI. It was determined that the PSQI score of those aged 24-25 was higher than those aged 22-23. It was determined that women's sitting subdimension scores were higher than men's.

The PSQI, Mental Endurance Inventory in Sports, Vigorous Physical Activity, Moderate Physical Activity sub-dimension scores of those who do active sports as a professional or amateur are higher than those who do not. Confidence sub-dimension score of those who do swimming-diving sports is higher than those who do football and other team sports. The Continuity sub-dimension score of those who play football is lower than those who do other sports. Those who do other sports have a higher Sports Mental Endurance Inventory score than those who do football and other team sports. The Severe Physical Activity sub-dimension score of those who do not do sports is lower than those who do swimming-diving and other sports. The Moderate Vigorous Physical Activity sub-dimension score of those who do not do sports is lower than those who do tennis, badminton and other sports. The Sitting Time sub-dimension score of those who do not do sports is higher than those who do football, athletics, other and other team sports. Those who do not do sports have higher PUKI scores than those who do football, swimming-diving, tennis-badminton, winter sports, other and other team sports. The Confidence sub-dimension score of those who start sports at the age of 7 and younger is higher than those who start sports at the age of 17 and above. Those who start sports between the ages of 8-11 have a higher Moderate Vigorous Physical Activity sub-dimension score than those who start at the age of 17 and above. Confidence sub-dimension score of those who train 1-2 days a week is lower than those who train 3-4 days a week. In addition, the Confidence sub-dimension score of those who train 5-6 days a week is higher than all other groups. The Severe Physical Activity sub-dimension score of those who train 1-2 days a week is lower than those who train 3-4 days a week and 5-6 days a week. The Moderate Vigorous Physical Activity sub-dimension score of those who train 1-2 days a week is lower than those who train 3-4 days a week and 5-6 days a week. Total Physical Activity score of those who train 1-2 days a week is lower than those who train 3-4 days a week and 5-6 days a week. No statistically significant difference was found between the smoking status groups in terms of scale and subdimension scores. In addition, it was determined that the walking sub-dimension scores of those who used alcohol were lower than those who did not use alcohol.