[Seasons, circadian rhythms, sleep and suicidal behaviors vulnerability]

Area of Science:

• Psychiatry
• Public Health
• Chronobiology

Background:

• Suicidal behaviors represent a significant public health challenge.
• Identifying suicide risk factors is crucial for effective prevention strategies.
• Seasonality, circadian rhythms, and sleep abnormalities are linked to psychiatric disorders.

Purpose of the Study:

• To review and characterize the associations between seasonality, circadian rhythms, sleep, and suicidal behaviors.
• To explore the influence of these factors on suicide attempts and completed suicides.

Main Methods:

• Conducted a literature search from 1973 to 2015 in PubMed.
• Used keywords: "suicide" OR "suicidality" OR "suicide attempts" OR "suicidal behavior" AND "circadian rhythms" OR "seasons" OR "sleep".

Main Results:

• Suicide rates exhibit seasonality, with peaks in spring and autumn, influenced by gender and depressive symptoms.
• Circadian variations in suicide rates exist, with different peaks for age groups and completed suicides versus attempts.
• Sleep disorders (insomnia, sleep deprivation) are common suicide risk factors, potentially independent of depression.
• Biomarkers like melatonin, serotonin, and cortisol may play a role in circadian suicide variations.
• Climatic and biological factors (sunshine, daylight, temperature) influence suicide behaviors.
• Chronotherapeutics show potential efficacy in reducing suicidal behaviors.

Conclusions:

• Suicide seasonality and circadian distribution are well-documented, varying by behavior intensity and age.
• Sleep disorders are significant suicide risk factors.
• Understanding these temporal patterns can improve suicide prevention and reduce mortality.