Can situational stress cause insomnia even after the stresser goes away for weeks or months. ?

Possible: That is possible, but if it has been a long time, it is more likely that the insomnia is related to another underlying problem. A primary care doctor, psychiatrist, sleep physician may all be helpful in determining exactly what is going on.

Stress: Once you develop poor sleeping habits it is difficult for your brain to break the cycle but with patience and good lifestyle habits you will likely return to quality sleep. Exercise daily before evening, no caffeine after 3pm, no alcohol in the evening, no naps, go to bed at the same time every night including weekends and when you wake during the night condition yourself to think positively.