We compare temperatures derived from simultaneous observations of 25 OH and two O₂ mesospheric airglow bands taken with the X-shooter spectrograph at the Very Large Telescope in Chile. Considering emission and temperature profile data from the radiometer SABER on the TIMED satellite, we find significant time-dependent non-thermal contributions to the OH-based temperatures, especially for bands originating from high vibrational levels. Many studies of the mesopause region are affected.