The aim of the study was to determine the convergent validity of a portable polysomnograph and an accelerometer for measuring sleep efficiency and movement in college students. Volunteers were 29 healthy students (males = 15, females = 14) who simultaneously wore the Nox T3 portable polysomnograph and the ActiGraph wGT3X-BT accelerometer. Both devices recorded "x," "y," and "z" coordinates at 10 Hz starting at 20:00:00 until the following morning. Repeated measures, concordance correlation coefficient, graphical, mixed-model, and Bayesian approaches were used to determine convergent validity. The sleep efficiency recorded by the Nox T3 was lower than the recorded by the ActiGraph wGT3X-BT (73.9 ± 24.3% vs. 86.1 ± 9.8%, p = 0.024; 95%CI = 1.8, 22.7), and both devices showed a poor concordance correlation coefficient (-0.09, 95%CI = -0.29, 0.13). The sleep monitor devices should not be used interchangeably to determine sleep efficiency and movement in college students.