My daughter is of 1yr 9 months .... she doesn't sleep at night constantly. She sleep disturbed and always wakes up midnight.. I am very much tensed... Why this is happening????

Is she watching ipad or tv during the day time? If yes, try to cut down as too much stimulation will affect their sleep at night as too much brain activity. Secondly, when her constantly waking up at night, you will also be tired and exhausted thus feeling very tensed. Try diffusing some lavendar oil, it helps to soothe and relax.