Office hours are one of the most common support mechanisms found in courses. Despite the prevalence of office hours in life sciences classes, there has been little investigation of how science, technology, engineering, and math (STEM) students perceive office hours, particularly at non--research intensive universities or other institutions where a majority of students attend office hours. We surveyed more than 500 students, representing most life sciences majors at a comprehensive university, to investigate their motivations and barriers for attending office hours. We then compared instructors' perceptions to students' conceptions of office hours. We identified key themes in student and instructor comments using inductive, grounded theory, finding that students view a more limited range of benefits for office hours than instructors. Students likewise cited a larger number of barriers for attending than instructors perceived. In addition, while there were minimal differences in rates of office hours attendance and perception of office hours based on key demographic factors, we identify areas where students of different class years and gender perceive differences, suggesting areas of future research. Finally, we explored students' views of in-person versus online office hours, providing insight for instructors to better reach all students.