Should Duzela Be Stopped Causing Restlessness And Sleep Disturbances?

Hi Doctor, kind Regards. My father is 60 years old & since 2 years he is taking Duzela 20 mg for depression n anxiety disorder ( prescribed by neurologist ). Hence this drug is causing him prominent restlessness & sleep disturbances...should he continue the drug or stop it ...or gradually decrese the dosage?? Please advice me for the same. Thank you sir.