13 weeks pregnant. i can't sleep through the night. is it safe to take unisom?

Unisom: When using meds in pregnancy, we need to know the fda pregnancy category. Category a means there are studies or know history of pregnant women on the drug and no problems with the baby-but this category is rare as no one does studies on pregnant women, so the next best is studies in pregnant mammal animals, that show no problem (cat b), ..Unisom is safe to take. It is a category b. Discuss w gyn!