My first thought here is they are not getting in enough physical play time, or fresh out door air, take them to the park for 2-3 hours, a pool, get outside, to wear them out so that they are tiredand sleep through the night, epecially at 3, that is high energy age. What does you hubby do with them when he is alone with them for the day?
What time do they get up in the morning?
Drop the day time nap is there is one.
Monster spray drop it not an issue right now, by go though all that.
If they are crying out for you two, then start a bedtime ritual each night, dim the lites in the whole house/apartent, tv, stereos off, and read a few bedtime stories with them sitting on your laps or in a rocking chair, every night.