International Journal of Bipolar Disorders (Sep 2021)
Variations in seasonal solar insolation are associated with a history of suicide attempts in bipolar I disorder
- Michael Bauer,
- Tasha Glenn,
- Eric D. Achtyes,
- Martin Alda,
- Esen Agaoglu,
- Kürşat Altınbaş,
- Ole A. Andreassen,
- Elias Angelopoulos,
- Raffaella Ardau,
- Edgar Arrua Vares,
- Memduha Aydin,
- Yavuz Ayhan,
- Christopher Baethge,
- Rita Bauer,
- Bernhard T. Baune,
- Ceylan Balaban,
- Claudia Becerra-Palars,
- Aniruddh P. Behere,
- Prakash B. Behere,
- Habte Belete,
- Tilahun Belete,
- Gabriel Okawa Belizario,
- Frank Bellivier,
- Robert H. Belmaker,
- Francesco Benedetti,
- Michael Berk,
- Yuly Bersudsky,
- Şule Bicakci,
- Harriet Birabwa-Oketcho,
- Thomas D. Bjella,
- Conan Brady,
- Jorge Cabrera,
- Marco Cappucciati,
- Angela Marianne Paredes Castro,
- Wei-Ling Chen,
- Eric Y. Wo Cheung,
- Silvia Chiesa,
- Marie Crowe,
- Alessandro Cuomo,
- Sara Dallaspezia,
- Maria Del Zompo,
- Pratikkumar Desai,
- Seetal Dodd,
- Markus Donix,
- Bruno Etain,
- Andrea Fagiolini,
- Frederike T. Fellendorf,
- Ewa Ferensztajn-Rochowiak,
- Jess G. Fiedorowicz,
- Kostas N. Fountoulakis,
- Mark A. Frye,
- Pierre A. Geoffroy,
- Ana Gonzalez-Pinto,
- John F. Gottlieb,
- Paul Grof,
- Bartholomeus C. M. Haarman,
- Hirohiko Harima,
- Mathias Hasse-Sousa,
- Chantal Henry,
- Lone Høffding,
- Josselin Houenou,
- Massimiliano Imbesi,
- Erkki T. Isometsä,
- Maja Ivkovic,
- Sven Janno,
- Simon Johnsen,
- Flávio Kapczinski,
- Gregory N. Karakatsoulis,
- Mathias Kardell,
- Lars Vedel Kessing,
- Seong Jae Kim,
- Barbara König,
- Timur L. Kot,
- Michael Koval,
- Mauricio Kunz,
- Beny Lafer,
- Mikael Landén,
- Erik R. Larsen,
- Melanie Lenger,
- Ute Lewitzka,
- Rasmus W. Licht,
- Carlos Lopez-Jaramillo,
- Alan MacKenzie,
- Helle Østergaard Madsen,
- Simone Alberte Kongstad A. Madsen,
- Jayant Mahadevan,
- Agustine Mahardika,
- Mirko Manchia,
- Wendy Marsh,
- Monica Martinez-Cengotitabengoa,
- Klaus Martiny,
- Yuki Mashima,
- Declan M. McLoughlin,
- Ybe Meesters,
- Ingrid Melle,
- Fátima Meza-Urzúa,
- Mok Yee Ming,
- Scott Monteith,
- Muthukumaran Moorthy,
- Gunnar Morken,
- Enrica Mosca,
- Anton A. Mozzhegorov,
- Rodrigo Munoz,
- Starlin V. Mythri,
- Fethi Nacef,
- Ravi K. Nadella,
- Takako Nakanotani,
- René Ernst Nielsen,
- Claire O‘Donovan,
- Adel Omrani,
- Yamima Osher,
- Uta Ouali,
- Maja Pantovic-Stefanovic,
- Pornjira Pariwatcharakul,
- Joanne Petite,
- Andrea Pfennig,
- Yolanda Pica Ruiz,
- Maximilian Pilhatsch,
- Marco Pinna,
- Maurizio Pompili,
- Richard Porter,
- Danilo Quiroz,
- Francisco Diego Rabelo-da-Ponte,
- Raj Ramesar,
- Natalie Rasgon,
- Woraphat Ratta-apha,
- Michaela Ratzenhofer,
- Maria Redahan,
- M. S. Reddy,
- Andreas Reif,
- Eva Z. Reininghaus,
- Jenny Gringer Richards,
- Philipp Ritter,
- Janusz K. Rybakowski,
- Leela Sathyaputri,
- Ângela M. Scippa,
- Christian Simhandl,
- Emanuel Severus,
- Daniel Smith,
- José Smith,
- Paul W. Stackhouse,
- Dan J. Stein,
- Kellen Stilwell,
- Sergio Strejilevich,
- Kuan-Pin Su,
- Mythily Subramaniam,
- Ahmad Hatim Sulaiman,
- Kirsi Suominen,
- Andi J. Tanra,
- Yoshitaka Tatebayashi,
- Wen Lin Teh,
- Leonardo Tondo,
- Carla Torrent,
- Daniel Tuinstra,
- Takahito Uchida,
- Arne E. Vaaler,
- Julia Veeh,
- Eduard Vieta,
- Biju Viswanath,
- Maria Yoldi-Negrete,
- Oguz Kaan Yalcinkaya,
- Allan H. Young,
- Yosra Zgueb,
- Peter C. Whybrow
Affiliations
- Michael Bauer
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Tasha Glenn
- ChronoRecord Association
- Eric D. Achtyes
- Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine
- Martin Alda
- Department of Psychiatry, Dalhousie University
- Esen Agaoglu
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Kürşat Altınbaş
- Department of Psychiatry, Selcuk University Faculty of Medicine, Mazhar Osman Mood Center
- Ole A. Andreassen
- NORMENT Centre, Division of Mental Health and Addiction, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo
- Elias Angelopoulos
- Department of Psychiatry, National and Capodistrian University of Athens, Medical School, Eginition Hospital
- Raffaella Ardau
- Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari
- Edgar Arrua Vares
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Memduha Aydin
- Department of Psychiatry, Selcuk University Faculty of Medicine
- Yavuz Ayhan
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Christopher Baethge
- Department of Psychiatry and Psychotherapy, University of Cologne Medical School
- Rita Bauer
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Bernhard T. Baune
- Department of Psychiatry, University of Münster
- Ceylan Balaban
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Johann Wolfgang Goethe-Universität Frankfurt am Main
- Claudia Becerra-Palars
- National Institute of Psychiatry “Ramón de la Fuente Muñiz”
- Aniruddh P. Behere
- Child and Adolescent Psychiatry, Helen DeVos Children’s Hospital, Michigan State University-CHM
- Prakash B. Behere
- Department of Psychiatry, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences (Deemed University)
- Habte Belete
- Department of Psychiatry, College of Medicine and Health Sciences, Bahir Dar University
- Tilahun Belete
- Department of Psychiatry, College of Medicine and Health Sciences, Bahir Dar University
- Gabriel Okawa Belizario
- Bipolar Disorder Research Program, Department of Psychiatry, University of São Paulo Medical School
- Frank Bellivier
- Département de Psychiatrie et de Médecine Addictologique, Assistance Publique-Hôpitaux de Paris, INSERM UMR-S1144, Université de Paris, FondaMental Foundation
- Robert H. Belmaker
- Professor Emeritus of Psychiatry, Ben Gurion University of the Negev
- Francesco Benedetti
- University Vita-Salute San Raffaele
- Michael Berk
- Deakin University, IMPACT-The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health
- Yuly Bersudsky
- Department of Psychiatry, Faculty of Health Sciences, Beer Sheva Mental Health Center, Ben Gurion University of the Negev
- Şule Bicakci
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Harriet Birabwa-Oketcho
- Butabika Hospital
- Thomas D. Bjella
- NORMENT Centre, Division of Mental Health and Addiction, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo
- Conan Brady
- Department of Psychiatry, Trinity College Dublin, St Patrick’s University Hospital
- Jorge Cabrera
- Mood Disorders Clinic, Dr. Jose Horwitz Psychiatric Institute
- Marco Cappucciati
- Department of Mental Health and Substance Abuse
- Angela Marianne Paredes Castro
- Deakin University, IMPACT-The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health
- Wei-Ling Chen
- Department of Psychiatry, Chiayi Branch, Taichung Veterans General Hospital
- Eric Y. Wo Cheung
- Private Practice
- Silvia Chiesa
- Department of Mental Health and Substance Abuse
- Marie Crowe
- Department of Psychological Medicine, University of Otago
- Alessandro Cuomo
- Department of Molecular Medicine, University of Siena School of Medicine
- Sara Dallaspezia
- Psychiatry and Clinical Psychobiology, Division of Neuroscience, San Raffaele Scientific Institute
- Maria Del Zompo
- Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari
- Pratikkumar Desai
- Pine Rest Christian Mental Health Services
- Seetal Dodd
- Deakin University, IMPACT-The Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health
- Markus Donix
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Bruno Etain
- Département de Psychiatrie et de Médecine Addictologique, Assistance Publique-Hôpitaux de Paris, INSERM UMR-S1144, Université de Paris, FondaMental Foundation
- Andrea Fagiolini
- Department of Molecular Medicine, University of Siena School of Medicine
- Frederike T. Fellendorf
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Ewa Ferensztajn-Rochowiak
- Department of Adult Psychiatry, Poznan University of Medical Sciences
- Jess G. Fiedorowicz
- Department of Psychiatry, School of Epidemiology and Public Health, University of Ottawa
- Kostas N. Fountoulakis
- 3rd Department of Psychiatry, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki
- Mark A. Frye
- Department of Psychiatry and Psychology, Mayo Clinic Depression Center, Mayo Clinic
- Pierre A. Geoffroy
- Département de Psychiatrie et d’addictologie, AP-HP, Hopital Bichat-Claude Bernard
- Ana Gonzalez-Pinto
- BIOARABA, Department of Psychiatry, University Hospital of Alava, University of the Basque Country, CIBERSAM
- John F. Gottlieb
- Department of Psychiatry, Feinberg School of Medicine, Northwestern University
- Paul Grof
- Mood Disorders Center of Ottawa and the Department of Psychiatry, University of Toronto
- Bartholomeus C. M. Haarman
- Department of Psychiatry, University Medical Center Groningen, University of Groningen
- Hirohiko Harima
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital
- Mathias Hasse-Sousa
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Chantal Henry
- Department of Psychiatry, GHU Paris Psychiatrie & Neurosciences
- Lone Høffding
- Department of Clinical Research, University of Southern Denmark
- Josselin Houenou
- Université Paris Est Créteil, INSERM, IMRB, Translational Neuropsychiatry, Fondation FondaMental
- Massimiliano Imbesi
- Department of Mental Health and Substance Abuse
- Erkki T. Isometsä
- Department of Psychiatry, University of Helsinki and Helsinki University Hospital
- Maja Ivkovic
- University Clinical Center of Serbia, Clinic for Psychiatry
- Sven Janno
- Department of Psychiatry, University of Tartu
- Simon Johnsen
- Unit for Psychiatric Research, Aalborg University Hospital
- Flávio Kapczinski
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Gregory N. Karakatsoulis
- 3rd Department of Psychiatry, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki
- Mathias Kardell
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg
- Lars Vedel Kessing
- Copenhagen Affective Disorder Research Center (CADIC), Psychiatric Center Copenhagen, Rigshospitalet
- Seong Jae Kim
- Department of Psychiatry, Cheongju Hospital
- Barbara König
- BIPOLAR Zentrum Wiener Neustadt
- Timur L. Kot
- Khanty-Mansiysk Clinical Psychoneurological Hospital
- Michael Koval
- Department of Neuroscience, Michigan State University
- Mauricio Kunz
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Beny Lafer
- Bipolar Disorder Research Program, Department of Psychiatry, University of São Paulo Medical School
- Mikael Landén
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg
- Erik R. Larsen
- Mental Health Department Odense, University Clinic and Department of Regional Health Research, University of Southern Denmark
- Melanie Lenger
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Ute Lewitzka
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Rasmus W. Licht
- Psychiatry, Aalborg University Hospital
- Carlos Lopez-Jaramillo
- Mood Disorders Program, Hospital Universitario San Vicente Fundación, Research Group in Psychiatry, Department of Psychiatry, Faculty of Medicine, Universidad de Antioquia
- Alan MacKenzie
- Forensic Psychiatry, University of Glasgow, NHS Greater Glasgow and Clyde
- Helle Østergaard Madsen
- Copenhagen University Hospitals, Psychiatric Centre Copenhagen
- Simone Alberte Kongstad A. Madsen
- Unit for Psychiatric Research, Aalborg University Hospital
- Jayant Mahadevan
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Agustine Mahardika
- Department of Psychiatry, Faculty of Medicine, Mataram University
- Mirko Manchia
- Department of Pharmacology, Dalhousie University
- Wendy Marsh
- Department of Psychiatry, University of Massachusetts Medical School
- Monica Martinez-Cengotitabengoa
- Osakidetza, Basque Health Service, BioAraba Research Institute, University of the Basque Country
- Klaus Martiny
- Copenhagen University Hospitals, Psychiatric Centre Copenhagen
- Yuki Mashima
- Department of Neuropsychiatry, Keio University School of Medicine
- Declan M. McLoughlin
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, St Patrick’s University Hospital
- Ybe Meesters
- Department of Psychiatry, University Medical Center Groningen, University of Groningen
- Ingrid Melle
- NORMENT Centre, Division of Mental Health and Addiction, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo
- Fátima Meza-Urzúa
- National Institute of Psychiatry “Ramón de la Fuente Muñiz”
- Mok Yee Ming
- Department of General Psychiatry, Mood Disorders Unit, Institute of Mental Health
- Scott Monteith
- Michigan State University College of Human Medicine
- Muthukumaran Moorthy
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Gunnar Morken
- Department of Mental Health, Norwegian University of Science and Technology-NTNU
- Enrica Mosca
- Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari
- Anton A. Mozzhegorov
- Soviet Psychoneurological Hospital
- Rodrigo Munoz
- Department of Psychiatry, University of California San Diego
- Starlin V. Mythri
- Asha Bipolar Clinic, Asha Hospital
- Fethi Nacef
- Razi Hospital, Faculty of Medicine, University of Tunis-El Manar
- Ravi K. Nadella
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Takako Nakanotani
- Affective Disorders Research Project, Tokyo Metropolitan Institute of Medical Science
- René Ernst Nielsen
- Psychiatry, Aalborg University Hospital
- Claire O‘Donovan
- Department of Psychiatry, Dalhousie University
- Adel Omrani
- Tunisian Bipolar Forum
- Yamima Osher
- Department of Psychiatry, Faculty of Health Sciences, Beer Sheva Mental Health Center, Ben Gurion University of the Negev
- Uta Ouali
- Razi Hospital, Faculty of Medicine, University of Tunis-El Manar
- Maja Pantovic-Stefanovic
- University Clinical Center of Serbia, Clinic for Psychiatry
- Pornjira Pariwatcharakul
- Department of Psychiatry, Faculty of Medicine, Siriraj Hospital, Mahidol University
- Joanne Petite
- Department of Psychiatry, Dalhousie University
- Andrea Pfennig
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Yolanda Pica Ruiz
- Hospital “Ángeles del Pedregal”
- Maximilian Pilhatsch
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Marco Pinna
- Section of Psychiatry, Department of Medical Science and Public Health, University of Cagliari
- Maurizio Pompili
- Department of Neurosciences, Mental Health and Sensory Organs, Sant’Andrea Hospital, Sapienza University of Rome
- Richard Porter
- Department of Psychological Medicine, University of Otago
- Danilo Quiroz
- Deparment of Psychiatry, Diego Portales University
- Francisco Diego Rabelo-da-Ponte
- Department of Psychiatry, Universidade Federal do Rio Grande do Sul
- Raj Ramesar
- SA MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Department of Pathology, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town
- Natalie Rasgon
- Department of Psychiatry and Behavioral Sciences, Stanford School of Medicine
- Woraphat Ratta-apha
- Department of Psychiatry, Faculty of Medicine, Siriraj Hospital, Mahidol University
- Michaela Ratzenhofer
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Maria Redahan
- Department of Psychiatry, Trinity College Dublin, St Patrick’s University Hospital
- M. S. Reddy
- Asha Bipolar Clinic, Asha Hospital
- Andreas Reif
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Johann Wolfgang Goethe-Universität Frankfurt am Main
- Eva Z. Reininghaus
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University Graz
- Jenny Gringer Richards
- Departments of Psychiatry, Epidemiology, and Internal Medicine, Iowa Neuroscience Institute, The University of Iowa
- Philipp Ritter
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Janusz K. Rybakowski
- Department of Adult Psychiatry, Poznan University of Medical Sciences
- Leela Sathyaputri
- Departments of Psychiatry, Epidemiology, and Internal Medicine, Iowa Neuroscience Institute, The University of Iowa
- Ângela M. Scippa
- Department of Neuroscience and Mental Health, Federal University of Bahia
- Christian Simhandl
- Bipolar Zentrum Wiener Neustadt, Sigmund Freud Privat Universität
- Emanuel Severus
- Department of Psychiatry and Psychotherapy, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden
- Daniel Smith
- Centre for Clinical Brain Sciences, University of Edinburgh
- José Smith
- Bipolar Disorder Program, Neuroscience Institute, Favaloro University
- Paul W. Stackhouse
- Science Directorate/Climate Science Branch, NASA Langley Research Center
- Dan J. Stein
- Department of Psychiatry, MRC Unit On Risk and Resilience in Mental Disorders, University of Cape Town
- Kellen Stilwell
- Pine Rest Christian Mental Health Services
- Sergio Strejilevich
- Bipolar Disorder Program, Neuroscience Institute, Favaloro University
- Kuan-Pin Su
- College of Medicine, China Medical University (CMU)
- Mythily Subramaniam
- Research Division, Institute of Mental Health
- Ahmad Hatim Sulaiman
- Department of Psychological Medicine, Faculty of Medicine, University of Malaya
- Kirsi Suominen
- Department of Social Services and Health Care, Psychiatry, City of Helsinki
- Andi J. Tanra
- Department of Psychiatry, Faculty of Medicine, Hasanuddin University
- Yoshitaka Tatebayashi
- Affective Disorders Research Project, Tokyo Metropolitan Institute of Medical Science
- Wen Lin Teh
- Research Division, Institute of Mental Health
- Leonardo Tondo
- McLean Hospital-Harvard Medical School
- Carla Torrent
- Clinical Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM
- Daniel Tuinstra
- Pine Rest Christian Mental Health Services
- Takahito Uchida
- Department of Neuropsychiatry, Keio University School of Medicine
- Arne E. Vaaler
- Department of Mental Health, Norwegian University of Science and Technology-NTNU
- Julia Veeh
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, University Hospital Frankfurt, Johann Wolfgang Goethe-Universität Frankfurt am Main
- Eduard Vieta
- Clinical Institute of Neuroscience, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERSAM
- Biju Viswanath
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS)
- Maria Yoldi-Negrete
- Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñíz
- Oguz Kaan Yalcinkaya
- Department of Psychiatry, Hacettepe University Faculty of Medicine
- Allan H. Young
- Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King’s College London
- Yosra Zgueb
- Razi Hospital, Faculty of Medicine, University of Tunis-El Manar
- Peter C. Whybrow
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles (UCLA)
- DOI
- https://doi.org/10.1186/s40345-021-00231-7
- Journal volume & issue
-
Vol. 9,
no. 1
pp. 1 – 14
Abstract
Abstract Background Bipolar disorder is associated with circadian disruption and a high risk of suicidal behavior. In a previous exploratory study of patients with bipolar I disorder, we found that a history of suicide attempts was associated with differences between winter and summer levels of solar insolation. The purpose of this study was to confirm this finding using international data from 42% more collection sites and 25% more countries. Methods Data analyzed were from 71 prior and new collection sites in 40 countries at a wide range of latitudes. The analysis included 4876 patients with bipolar I disorder, 45% more data than previously analyzed. Of the patients, 1496 (30.7%) had a history of suicide attempt. Solar insolation data, the amount of the sun’s electromagnetic energy striking the surface of the earth, was obtained for each onset location (479 locations in 64 countries). Results This analysis confirmed the results of the exploratory study with the same best model and slightly better statistical significance. There was a significant inverse association between a history of suicide attempts and the ratio of mean winter insolation to mean summer insolation (mean winter insolation/mean summer insolation). This ratio is largest near the equator which has little change in solar insolation over the year, and smallest near the poles where the winter insolation is very small compared to the summer insolation. Other variables in the model associated with an increased risk of suicide attempts were a history of alcohol or substance abuse, female gender, and younger birth cohort. The winter/summer insolation ratio was also replaced with the ratio of minimum mean monthly insolation to the maximum mean monthly insolation to accommodate insolation patterns in the tropics, and nearly identical results were found. All estimated coefficients were significant at p < 0.01. Conclusion A large change in solar insolation, both between winter and summer and between the minimum and maximum monthly values, may increase the risk of suicide attempts in bipolar I disorder. With frequent circadian rhythm dysfunction and suicidal behavior in bipolar disorder, greater understanding of the optimal roles of daylight and electric lighting in circadian entrainment is needed.
Keywords