Matthew was exposed to unimaginable scenes of pain and suffering in his job over more than a decade as a firefighter. The last straw came when he witnessed the death of a teenager – who was the same age as his son – from an overdose.

“The worst part is when you see an infant or a child die,” he told me during a visit. “Exposure to their family’s pain – and that you could not save that life – is very heartbreaking.” Matthew, for whom I’m using a pseudonym to protect his privacy, was being treated at my clinic for post-traumatic stress disorder and depression.