Lunar cycle effects on sleep and the file drawer problem

470 sleep EEGs from 366 healthy participants in a light-controlled sleep laboratory (see Experimental Procedures in Supplemental Information, published with this article online). Lunar classes were defined as previously [2], with lunar class 1 representing full moon ± 4 nights, lunar class 2 covering the waxing and waning moon periods (full moon ± 5–9 nights) and lunar class 3 representing new moon (full moon ± 10–14 nights). In contrast to the results reported by Cajochen et al. [2], we did not find any evidence for an influence of lunar class on objective sleep parameters (all P >0.1, Table 1). Data set 2 was also recorded in the Max Planck Institute of Psychiatry; however, in contrast to the first sample this data set included 757 sleep EEGs of 29 volunteers each of whom slept for 13–60 consecutive nights in the sleep laboratory, i.e. across all phases of the lunar cycle. Also in this data set we were not able to replicate any of the findings by Cajochen et al. [2] (Table 1). Data set 3 represents a sample recruited at the University of Basel. It includes sleep EEGs of 870 young, healthy volunteers who slept at home. Again, there was no indication of a significant effect of the lunar cycle on sleep variables (Table 1). In addition, oscillatory activity during NREM sleep did not differ between lunar classes in this data set (Figure S1). In particular, no effects were observed in the EEG delta band as reported by Cajochen et al. [2]. In sum, we were not able to replicate the large effects of lunar cycle on sleep EEG reported by Cajochen et al. [2] in three large samples consisting of 470, 757 and 870 sleep recordings: none of the variables that were reported to be affected by lunar cycle by Cajochen et al. yielded significant results in any of our samples. This also holds for alternative analyses with outlier exclusion and interaction analyses. Please note that for other sleep variables that were not significant in the data of Cajochen et al., some small and inconsistent effects and interactions with lunar class emerged (for details and discussion, see Supplemental Discussion). Even though exact values of power calculations have to be interpreted with caution due to differences in research designs, in our three samples we can exclude Popular beliefs about the influence of the full moon on humans exist, although no solid …