The study was conducted in October 2020 and March 2021 among Wroclaw Medical University students of different years and faculties. The objective of the study was to establish the relationship between some determinants, such as gender and the levels of physical activity, and the quality of sleep of medical students during the pandemic. Ultimately, 696 responses from October and 652 from March were included. To determine the level of physical activity, the International Physical Activity Questionnaire (IPAQ) was used, and for sleep quality, the Pittsburgh Sleep Quality Index (PSQI) was used. The findings pointed to a higher Total MET m/w (metabolic equivalent of task in minutes a week) in men compared to women in both study periods (2020: 1845.8 to 1542.5, p = 0.009; 2021: 2040.7 to 1826.6, p = 0.025). This was mainly due to a higher Vigorous Exercises MET m/w in men (2020: 837.3 to 635.8, p = 0.008; 2021: 773.3 to 490.3, p = 0.0006). Moreover, women had a lower quality of sleep resulting from problems in Habitual Sleep Efficiency, Sleep Disturbances, and Daytime Dysfunctions. An adequate level of physical activity and a good night’s rest are the fundaments of health; therefore, it is necessary to determine the causes of their deficiencies in order that we can counteract them.