The knowledge about the awakening of hibernating bats is not sufficient. Unknown are also factors affecting the cyclical nature of this process. The aim of the study was to determine the impact of changes of phases of the moon, and thus changes in the Earth's magnetic field on the behaviour of wintering common noctules Nyctalus noctula Schreber. Hibernation of 336 common noctules placed in the hibernation shed was investigated. The shed was equipped with loggers which measured temperature. Based on the temperature changes inside the shed, a drop or an increase in bat activity was determined. Periodicity of temperature increase was observed and it correlated with the current moon phases. The moon phase regarded as the bright referred to more than 70% of moon face illuminated (MFI). The significant temperature increase inside the shed was observed at 70% MFI. This is also when the bats demonstrated an increased activity. The observed differences in the temperature inside the shed during bright nights were statistically significant. The results of the research indicate that moon phases have influence on awakenings coordination in the wintering colony of noctule bat. This phenomenon causes difficulties in interpretation. If bats are in fact able to distinguish moon phases the moon appears to be the perfect tool to control their internal biological clock.