Image by eso.org.
A new study by T. Wehr found some evidence that lunar cycles can entrain mood cycles in patients with bipolar depression. Dr. Wehr found in some patients similar periodicities in their mood cycles which were synchronous with multiples of bi-weekly lunar tidal cycles:
T A Wehr; Bipolar mood cycles and lunar tidal cycles Molecular Psychiatry advance online publication 24 January 2017; doi: 10.1038/mp.2016.263