Sunlight and suicide

Ever since the 2001 attack on the World Trade Center, I have associated a bright, sunny day with disaster. I vividly remember what a beautiful morning that was -- a crystal blue cloudless sky, low humidity, and a cool, comfortable temperature. Who could be unhappy on such a marvelous day?

On the other hand, my experience living in a northern climate taught me that winter was another story. Getting up in the dark to go to school or work was a miserable experience, followed by coming home in the dark and endless hours of biting cold and bitter nights. I was not surprised to learn later in my residency training about seasonal affective disorder and about the effects of light on mood. With this background, I felt primed to write a column about a new study, "Direct Effect of Sunshine on Suicide" (JAMA Psychiatry 2014 Sept. 10 [doi:10.1001/jamapsychiatry.2014.1198]).

In this study, investigators looked at public records of confirmed suicides in Austria between January 1970 and May 2010.They gathered 40 years of daily sunlight data from 86 meteorological stations. The amount of sunlight was defined as the duration of time that light intensity was higher than 120 watts per square meter, which apparently is the amount of light typically seen just after sunrise or just before sunset. Using this information, they compared daily suicide rates with the average daily duration of sunshine. Since sunlight varies in both duration and intensity over the seasons, the researchers used statistical methods to compensate for this, which distinguished this work from previous similar suicide studies. The authors then compared suicide rates by gender and method.

There were 69,462 suicide deaths, the majority through violent means such as hanging, drowning, shooting, or jumping. Only a quarter of the deaths were through nonviolent means such as poisoning. A significant correlation was found between the daily suicide rate and the daily duration of sunshine, but the surprising result was that sunshine appeared to have both a provocative and a palliative effect. Suicide rates climbed with increasing sunshine during the 10 days leading up to a suicide for suicides as a whole, for suicide through violent means, and for women. Sunlight had no effect on suicides for nonviolent deaths.

As a group, there was a negative correlation with deaths for the 14-60 days prior to a given suicide. Violent suicides were less likely during this time. The effects of sunshine also were specific to gender. There was a negative correlation, or apparently a protective effect, for men but not for women in the preceding 14-60 days.

Many physiologic reasons explain why light can affect mood, such as disruption of circadian rhythms and altered melatonin levels, or disturbances in serotonin or monoamine systems. There have also been social explanations for why suicides show seasonal variation. The "winter blues" have been explained by the stress of holiday preparation and its associated high expectations, family conflict, and increased alcohol use around this time. The authors concluded that one reason sunlight may increase suicide rates is that sunlight may improve motivation before lifting mood, giving a person the impetus to act on self-destructive impulses.

How this relates to the use of light boxes to treat seasonal affective disorder remains to be seen. Traditionally, this intervention is favored because of the relatively few associated hazards and side effects compared to pharmacotherapy. This risk-benefit ratio may need to be reassessed as more studies address the sunlight-suicide connection. Still, given that these devices are not Food and Drug Administration‑regulated or approved, I doubt we will be seeing the equivalent of a “black box” warning anytime in the near future.

Dr. Hanson is a forensic psychiatrist and coauthor of “Shrink Rap: Three Psychiatrists Explain Their Work.” The opinions expressed are those of the author only, and do not represent those of any of Dr. Hanson's employers or consultees, including the Maryland Department of Health and Mental Hygiene or the Maryland Division of Correction.

Ever since the 2001 attack on the World Trade Center, I have associated a bright, sunny day with disaster. I vividly remember what a beautiful morning that was -- a crystal blue cloudless sky, low humidity, and a cool, comfortable temperature. Who could be unhappy on such a marvelous day?

On the other hand, my experience living in a northern climate taught me that winter was another story. Getting up in the dark to go to school or work was a miserable experience, followed by coming home in the dark and endless hours of biting cold and bitter nights. I was not surprised to learn later in my residency training about seasonal affective disorder and about the effects of light on mood. With this background, I felt primed to write a column about a new study, "Direct Effect of Sunshine on Suicide" (JAMA Psychiatry 2014 Sept. 10 [doi:10.1001/jamapsychiatry.2014.1198]).

In this study, investigators looked at public records of confirmed suicides in Austria between January 1970 and May 2010.They gathered 40 years of daily sunlight data from 86 meteorological stations. The amount of sunlight was defined as the duration of time that light intensity was higher than 120 watts per square meter, which apparently is the amount of light typically seen just after sunrise or just before sunset. Using this information, they compared daily suicide rates with the average daily duration of sunshine. Since sunlight varies in both duration and intensity over the seasons, the researchers used statistical methods to compensate for this, which distinguished this work from previous similar suicide studies. The authors then compared suicide rates by gender and method.

There were 69,462 suicide deaths, the majority through violent means such as hanging, drowning, shooting, or jumping. Only a quarter of the deaths were through nonviolent means such as poisoning. A significant correlation was found between the daily suicide rate and the daily duration of sunshine, but the surprising result was that sunshine appeared to have both a provocative and a palliative effect. Suicide rates climbed with increasing sunshine during the 10 days leading up to a suicide for suicides as a whole, for suicide through violent means, and for women. Sunlight had no effect on suicides for nonviolent deaths.

As a group, there was a negative correlation with deaths for the 14-60 days prior to a given suicide. Violent suicides were less likely during this time. The effects of sunshine also were specific to gender. There was a negative correlation, or apparently a protective effect, for men but not for women in the preceding 14-60 days.

Many physiologic reasons explain why light can affect mood, such as disruption of circadian rhythms and altered melatonin levels, or disturbances in serotonin or monoamine systems. There have also been social explanations for why suicides show seasonal variation. The "winter blues" have been explained by the stress of holiday preparation and its associated high expectations, family conflict, and increased alcohol use around this time. The authors concluded that one reason sunlight may increase suicide rates is that sunlight may improve motivation before lifting mood, giving a person the impetus to act on self-destructive impulses.

How this relates to the use of light boxes to treat seasonal affective disorder remains to be seen. Traditionally, this intervention is favored because of the relatively few associated hazards and side effects compared to pharmacotherapy. This risk-benefit ratio may need to be reassessed as more studies address the sunlight-suicide connection. Still, given that these devices are not Food and Drug Administration‑regulated or approved, I doubt we will be seeing the equivalent of a “black box” warning anytime in the near future.

Dr. Hanson is a forensic psychiatrist and coauthor of “Shrink Rap: Three Psychiatrists Explain Their Work.” The opinions expressed are those of the author only, and do not represent those of any of Dr. Hanson's employers or consultees, including the Maryland Department of Health and Mental Hygiene or the Maryland Division of Correction.

Ever since the 2001 attack on the World Trade Center, I have associated a bright, sunny day with disaster. I vividly remember what a beautiful morning that was -- a crystal blue cloudless sky, low humidity, and a cool, comfortable temperature. Who could be unhappy on such a marvelous day?

On the other hand, my experience living in a northern climate taught me that winter was another story. Getting up in the dark to go to school or work was a miserable experience, followed by coming home in the dark and endless hours of biting cold and bitter nights. I was not surprised to learn later in my residency training about seasonal affective disorder and about the effects of light on mood. With this background, I felt primed to write a column about a new study, "Direct Effect of Sunshine on Suicide" (JAMA Psychiatry 2014 Sept. 10 [doi:10.1001/jamapsychiatry.2014.1198]).

In this study, investigators looked at public records of confirmed suicides in Austria between January 1970 and May 2010.They gathered 40 years of daily sunlight data from 86 meteorological stations. The amount of sunlight was defined as the duration of time that light intensity was higher than 120 watts per square meter, which apparently is the amount of light typically seen just after sunrise or just before sunset. Using this information, they compared daily suicide rates with the average daily duration of sunshine. Since sunlight varies in both duration and intensity over the seasons, the researchers used statistical methods to compensate for this, which distinguished this work from previous similar suicide studies. The authors then compared suicide rates by gender and method.

There were 69,462 suicide deaths, the majority through violent means such as hanging, drowning, shooting, or jumping. Only a quarter of the deaths were through nonviolent means such as poisoning. A significant correlation was found between the daily suicide rate and the daily duration of sunshine, but the surprising result was that sunshine appeared to have both a provocative and a palliative effect. Suicide rates climbed with increasing sunshine during the 10 days leading up to a suicide for suicides as a whole, for suicide through violent means, and for women. Sunlight had no effect on suicides for nonviolent deaths.

As a group, there was a negative correlation with deaths for the 14-60 days prior to a given suicide. Violent suicides were less likely during this time. The effects of sunshine also were specific to gender. There was a negative correlation, or apparently a protective effect, for men but not for women in the preceding 14-60 days.

Many physiologic reasons explain why light can affect mood, such as disruption of circadian rhythms and altered melatonin levels, or disturbances in serotonin or monoamine systems. There have also been social explanations for why suicides show seasonal variation. The "winter blues" have been explained by the stress of holiday preparation and its associated high expectations, family conflict, and increased alcohol use around this time. The authors concluded that one reason sunlight may increase suicide rates is that sunlight may improve motivation before lifting mood, giving a person the impetus to act on self-destructive impulses.

How this relates to the use of light boxes to treat seasonal affective disorder remains to be seen. Traditionally, this intervention is favored because of the relatively few associated hazards and side effects compared to pharmacotherapy. This risk-benefit ratio may need to be reassessed as more studies address the sunlight-suicide connection. Still, given that these devices are not Food and Drug Administration‑regulated or approved, I doubt we will be seeing the equivalent of a “black box” warning anytime in the near future.

Dr. Hanson is a forensic psychiatrist and coauthor of “Shrink Rap: Three Psychiatrists Explain Their Work.” The opinions expressed are those of the author only, and do not represent those of any of Dr. Hanson's employers or consultees, including the Maryland Department of Health and Mental Hygiene or the Maryland Division of Correction.