nevaeh75,
Are your children diagnosed with ADHD?
As Thunor said, Risperdal is rarely prescribed for ADHD. It *will* make them slow, have trouble focusing, and cause weight gain. Risperdal is commonly used for the rage of Tourette's syndrome (the one with tics) which sometimes accompanies ADHD. Is it possibly being used for that?
Otherwise, Risperdal might be used to help control extreme hyperactivity. It can help with that (and it can help too much as you are seeing with your child's sluggishness). However, it will make attention issues worse so it is rarely used.
I think you should talk to your doc about changing the medication (if it is, in fact, being prescribed for ADHD) and/or consider changing doctors. Are you currently using a psychiatrist?