Sunshine Directly Influences Suicide Incidence
Caroline Cassels
September 10, 2014
The amount of daily sunshine individuals receive appears to have a direct impact on suicide incidence, new research suggests.
A large, retrospective analysis of all officially confirmed suicides in Austria shows that the number of hours of daily sunshine and the number of daily suicides during a 40-year period were "highly correlated."
Researchers found there was a positive correlation between the number of suicides and hours of daily sunshine on the day of the suicide and up to 10 days before that seemed to facilitate suicide; sunshine occurring 14 to 60 days prior was associated with a reduction in suicides.
"Duration of daily sunshine was significantly correlated with suicide frequency independent of season, but effect sizes were low. Our data support the hypothesis that sunshine on the day of suicide and up to 10 days prior to suicide may facilitate suicide," the authors led by Benjamin Vyssoki, MD, Medical University of Vienna, write.
"More daily sunshine 14 to 60 days previously is associated with low rates of suicide. Our study also suggests that sunshine during this period may protect against suicide," they add.
The study was published online September 10 in JAMA Psychiatry.
The investigators point out that light interacts with brain serotonin systems and may influence serotonin-related behaviors, including mood and impulsiveness, which can play a role in suicide.
They also note that their previous research demonstrated that seasonal changes in sunshine are associated with seasonal variations in suicide incidence, particularly violent suicides.
To further confirm the hypothesis that sunshine has a direct role in the variation in suicide incidence, the investigators looked at the relationship between the number of suicides and duration of sunshine after removing seasonal variations in sunshine and suicide numbers.
The study included data on 69,462 officially confirmed suicides in Austria between January 1970 and May 2010. Hours of sunshine per day were calculated from 86 representative meteorologic stations.
Daily number of suicides and daily duration of sunshine were differentiated to remove variation in sunshine and variation in suicide incidence introduced by season.
Results revealed that the duration of sunshine influenced suicide rates independently of seasonal rhythms, the investigators report.
"Moreover, they show that sunshine has a bimodal effect on suicidal behavior as an increase in suicide was found in short time scales, while after longer periods more sunshine was associated with decreased suicide.
"Further research is warranted to determine which patients with severe episodes of depression are most susceptible to the suicide-triggering effects of sunshine," the investigators write.
The authors report no relevant financial relationships.
JAMA Psychiatry. Published online September 10, 2014. Abstract
Caroline Cassels
September 10, 2014
The amount of daily sunshine individuals receive appears to have a direct impact on suicide incidence, new research suggests.
A large, retrospective analysis of all officially confirmed suicides in Austria shows that the number of hours of daily sunshine and the number of daily suicides during a 40-year period were "highly correlated."
Researchers found there was a positive correlation between the number of suicides and hours of daily sunshine on the day of the suicide and up to 10 days before that seemed to facilitate suicide; sunshine occurring 14 to 60 days prior was associated with a reduction in suicides.
"Duration of daily sunshine was significantly correlated with suicide frequency independent of season, but effect sizes were low. Our data support the hypothesis that sunshine on the day of suicide and up to 10 days prior to suicide may facilitate suicide," the authors led by Benjamin Vyssoki, MD, Medical University of Vienna, write.
"More daily sunshine 14 to 60 days previously is associated with low rates of suicide. Our study also suggests that sunshine during this period may protect against suicide," they add.
The study was published online September 10 in JAMA Psychiatry.
The investigators point out that light interacts with brain serotonin systems and may influence serotonin-related behaviors, including mood and impulsiveness, which can play a role in suicide.
They also note that their previous research demonstrated that seasonal changes in sunshine are associated with seasonal variations in suicide incidence, particularly violent suicides.
To further confirm the hypothesis that sunshine has a direct role in the variation in suicide incidence, the investigators looked at the relationship between the number of suicides and duration of sunshine after removing seasonal variations in sunshine and suicide numbers.
The study included data on 69,462 officially confirmed suicides in Austria between January 1970 and May 2010. Hours of sunshine per day were calculated from 86 representative meteorologic stations.
Daily number of suicides and daily duration of sunshine were differentiated to remove variation in sunshine and variation in suicide incidence introduced by season.
Results revealed that the duration of sunshine influenced suicide rates independently of seasonal rhythms, the investigators report.
"Moreover, they show that sunshine has a bimodal effect on suicidal behavior as an increase in suicide was found in short time scales, while after longer periods more sunshine was associated with decreased suicide.
"Further research is warranted to determine which patients with severe episodes of depression are most susceptible to the suicide-triggering effects of sunshine," the investigators write.
The authors report no relevant financial relationships.
JAMA Psychiatry. Published online September 10, 2014. Abstract
