January 1 is unique among major holidays as a suicide flashpoint.
Every 40 seconds, someone in the world commits suicide. In the U.S., we attempt to kill ourselves more on Mondays, and more in the spring than any other season. But major holidays can be protective. We attempt suicide less on Christmas, Thanksgiving, and Fourth of July. One holiday stands opposite to that trend, though. On New Year's Day, compared to non-holidays, we see "significantly higher numbers of suicide attempts by overdose."
That's what emergency medicine physician Gillian Beauchamp and her colleagues at the University of Cincinnati found when they reviewed over one million "ingestion with suicide intent" reports to Poison Control. Those included prescription, non-prescription (lots of Tylenol cases), and street drug ingestions (but didn't include violent self-injury).
Suicide is perennially among the top 10 causes of death in the U.S., and worldwide around one million people kill themselves every year. Beauchamp told me that number is rising, so she's working to identify risk factors like these, times at which people are most likely make to attempts, to stem the rise. This sort of information can both inform prevention and make sure facilities are staffed and ready to handle surges of poisoning or suicidal ideation admissions at high risk times.