Ativan is a
benzodiazepine.
Diazepam (part of Depsonil DZ) is a long acting benzodiazepine. If I get such a patient in my practice, I would first change Depsonil DZ to plain Depsonil. Later on, I would substitute Ativan with a shorter acting medicine such as
Zolpidem.
I would check to see if there is a depressive or
anxiety disorder and whether Depsonil needs to be continued and what dosage.
I would give tips for good sleep (regular exercise but not in four hours before bedtime, fixed waking time, no day time sleep, no stimulants such as tea or coffee in the evening or at night, no alcohol as nightcap, relaxing bed time routine, quiet dark room and dry comfortable bedding, warm bath before sleep, going to bed only when sleepy).
Since you are taking these medicines for 15 years it may take some time, but you should be able to do it successfully under psychiatric guidance.
I hope this has answered your question.