Is it fine to take 2.5mg of Lexapro (antidepressant) instead of 5mg?

Hi, my aunt is taking Lexapro to help her with mild depression, and anxiety. Her main issue is insomnia, about 4 weeks now of very poor sleep (less than 3 hrs every day). She's taking Lexapro in the mornings, 5mg for 30 days. She says that she feels terribly drowsy, itching in the legs, trouble talking, lethargy, trouble concentrating; in her own words she felt disconnected from the world. We are having trouble communicating with her doctor. Since she's supposed to take the pill in the mornings, is it fine if she takes half of it? (2.5 mg)