Writing in the New York Times' "Well" blog, David Dobbs explores why the number of suicides tends to increase by 15% in May and June, despite conventional wisdom that better weather tends to lift many people's spirits.
According to psychologist Kay Redfield Jamison—who has written about the phenomenon in her book Night Falls Fast—spring may bring on a "broken promise effect" for many people who suffer from depression: Namely, that they expect better weather to bring them relief, and they are distraught when it fails to do so. Moreover, psychiatrists have long noted a rise in "manic agitation" among patients with bipolar disorder and depression in the springtime.
Another theory suggests that the seasonal drop in the sleep-inducing hormone melatonin may disrupt rest and further agitate those already suffering from psychotic disorders.
Other studies suggest that spring may lead to a spike in inflammatory chemical activity, which reduces the neurotransmitter serotonin and halts the growth of new brain cells—two symptoms of a patient with depression. This spike may be linked to tree pollen, according to University of Maryland psychiatrist Teodor Postolache.
Postolache conducted a study linking high pollen counts with high seasonal suicide rates by studying the brains of 34 suicide victims.
Johns Hopkins psychiatrist Adam Kaplin says the spring-related inflammation is the result of entering sun-filled days after developing a vitamin D deficiency over the winter. Or the "answer to this puzzle is probably some form of 'all of the above,'" Kaplin said (Dobbs, "Well," New York Times, 6/24).