Mirtazapine dosage for insomnia is generally evaluated based on the body’s resistance to Mirtazapine. Mirtazapine is a medication for depression that is used for nighttime dosing as it aids in improving sleep. If Mirtazapine is used to treat insomnia, the typical starting dosage is from 15 mg. If after taking 15 mg of Mirtazapine for a week, you still can’t sleep at night. At this point, you can adjust the mirtazapine to 30 mg and take it for a week to observe sleep. Mirtazapine can be taken in therapeutic amounts up to 45 mg. Taking too much Mirtazapine can cause adverse reactions such as drowsiness, sedation, dry mouth, weight gain, increased appetite, dizziness and fatigue, postural hypotension, and emotional irritability. Mirtazapine is contraindicated in people who are allergic to it. Mirtazapine should always be taken under the guidance of a doctor.