Commentary on “Synchrony Between Bipolar Mood Cycles and Lunar Tidal Cycles Ended After Initiation of Light Treatment and Treatment of Hypothyroidism”KAHN, DAVID A. MDJournal of Psychiatric Practice: November 2019 - Volume 25 - Issue 6 - p 475–480 doi: 10.1097/PRA.0000000000000424 Clinical Case Discussions Buy Abstract Author InformationAuthors Article MetricsMetrics According to a recent report, mood cycles in a group of patients with rapid cycling bipolar disorder oscillated in synchrony with lunar gravimetric tides. Mood switches in a 67-year-old woman with rapid cycling bipolar II disorder on lithium maintenance treatment were assessed with a χ2 periodogram and a χ2 analysis of the mood switches in relation to the lunar tidal cycle. During a period when she was treated with nortriptyline and her thyroid-stimulating hormone levels were elevated, her mood switches had a significant (P<0.05) 29- to 30-day periodicity, and the χ2 analysis showed that the switches were distributed nonrandomly in relation to the spring-neap lunar tidal cycle (P<0.0001); 14 of 15 switches occurred within 2 days of the spring tides. After nortriptyline was discontinued, thyroid-stimulating hormone levels were normalized with treatment with levothyroxine, and consistent bright light treatment was started, the synchrony between mood cycles and lunar cycles disappeared, and rapid cycling eventually stopped. The possibility that lunar mood cycling is sometimes contingent on antidepressant treatment, decreased thyroid function, and certain types of light-dark cycles needs to be considered in future research on lunar tidal influences on the course of bipolar illness. KAHN: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY D.H.A. and T.A.W. wrote the manuscript, did the statistical analyses, and created the figures. E.M.A. was the clinician and collected the data. The authors declare no conflicts of interest. Please send correspondence to: David H. Avery, MD, Psychiatric Medicine Associates, 1505 Westlake Avenue North, Suite 920, Seattle, WA 98109 (e-mail: email@example.com). Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.