Two months after knowing that his son was suffering from leukemia, a 45 year old father presents with sleep deprivation, lethargy, headache, and low mood. He interacts reasonably well with others, but has absented himself from work. The most probable diagnosis is:

Here, the diagnosis is adjustment disorder. The symptoms are not severe enough to qualify for the diagnosis of depression and there is a clear history of a stressor (diagnosis of leukemia in son). The symptoms of adjustment disorder usually sta within 3 months of the stressor