NOTTINGHAM, United Kingdom — While most people tend to assume suicide rates are highest during the winter, spring and early summer are actually the seasons when suicidal behaviors peak. This observation has always baffled scientists and doctors alike, but researchers from the University of Nottingham are shedding light on this delicate but incredibly important topic. Study authors found suicidal thoughts peak during the winter — just a few months before the established jump in suicidal behaviors.
Interestingly, researchers also showed the daily peak in suicidal thoughts is between 4 a.m. and 5 a.m., with the highest actual risk of suicidal behavior taking place between 4 a.m. and 6 a.m.
This work was conducted in collaboration with the University of Amsterdam and Harvard University, in an effort to examine the seasonal paths of suicidal thoughts and identify exactly when suicidal thoughts peak during the year, as well as the time of day these thoughts tend to be at their most intense.
So, over a span of six years, the team gathered responses from more than 10,000 people living in the U.S., U.K., and Canada. Participants filled out various questionnaires and completed tasks pertaining to their moods, thoughts, and ideations surrounding suicide and self-harm using the Project Implicit Health Database (PIH).
Suicidal thoughts peak at the end of the year
The research team ultimately found that suicidal thoughts tend to be at their highest in the winter — specifically in December. From there, they put together a conceptual model for why suicidal behavior takes a few months before it reaches a tipping point. Researchers also noted a general uptick in negative self-harm cognitions across the six-year period of the study.
“It is well documented that winter is the time when people with mental health problems may struggle with worsening mood and depression, indeed Seasonal Affective Disorder is a recognized issue related to the change in season that affects many people’s mental health. So, it may come as a surprise that spring, a time when you would assume people’s mood lifts, is actually the time of year when people are most at risk of taking their own lives,” says study leader Dr. Brian O’Shea from the University of Nottingham in a media release.
“The reasons for this are complex, but our research shows that suicidal thoughts and mood are the worst in December and the best in June. Between these two points, there is a heightened risk of suicidal behavior, and we feel this is occurring because the gradual improvements in their mood and energy may enable them to plan and engage in a suicide attempt. The relative comparison between the self and others’ mood improving at a perceived greater rate are complementary possibilities that need further testing,” the researcher continues.
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Study authors created a series of online tasks intended to examine the temporal dynamics of explicit and implicit self-harm cognitions, examining explicit cognition via direct questions regarding one’s mood, suicide, and self-harm using a standard scale from one to five. More specifically, the team explored implicit cognition using a reaction time task in which participants had to sort words relating to themselves in real-time with death and life words.
Those participating in these samples came from three groups: past suicide attempters, suicide ideation and/or non-suicidal self-injury, or no previous self-harm or suicidal thoughts or behaviors. Study authors discovered a general increase in negative self-harm cognitions across the six-year span, as well as seasonality effects for mood and desire to die, especially among those who previously made a suicide attempt.
All in all, researchers conclude this work points to a clear latency between the peak of explicit and implicit suicide cognition during the winter months and a subsequent peak in actual suicide attempts and suicide deaths come springtime. On a more scientific level, explicit suicide cognition, which usually peaks in December, preceded implicit self-harm associations, peaking in February. Both of those initial peaks precede the peak of suicide behaviors in spring and early summer.
Researchers observed similar delayed effects over a 24-hour period, with explicit suicidal cognition and mood peaking very early in the morning (4-5 a.m.) and implicit cognition lagging afterwards.
“This study is the first to look at temporal trends around mood and self-harm thoughts on such a large scale and really pinpoints times when intervention could be most beneficial,” Dr. O’Shea concludes.
The study is published in the journal Translational Psychiatry.
