I have problems sleeping at night and i tried unisom, but it made feel bad the next day & i was also very jittery. what could be the reason for that?

Med side effects: Unisom contains an antihistamine. Some people feel lousy when they take that type of med; depressed, jittery, anxious, or even hung over. It also makes the mouth dry. Kids, in particular, can have opposite reactions to antihistamines, getting excited instead of sleepy. Try something else-- maybe melatonin. If you have a doctor, ambien-type meds are better tolerated than antihistamines.

Anticholinergics: Many antihistamines have an anticholinergic effects to which some may be sensitive. The effects can be racing heart, dry mouth, constipation, urinary retention, not sweating, confusion and hallucinations.

Diphenhydramine: Is the same thing as Benadryl (diphenhydramine) which is an antihistamine. It is the sedating component of most over the counter sleeping preparations and does have anrticholinergic effects.