nightmares with adderall xr or guanfacine | ADHD Information

What are the nightmares about.  When we were trying the stimulants, my daughter went through a spell of having nightmares about worms.  They stopped when the med stopped.  A while afterwards, I found some research showing that the drug tended to cause nightmares about worms.  I thought it was a just a kids phase.  Unfortunately, I don't rememeber which med it was, as we went through quite a few.  She didn't have nightmares on Guanfacine.   The guanfacine can be causing the nightmares.  For some people, it activates the REM sleep more than normal.  My child always used to wake up at 3 am while taking guanfacine, and we had to add Benadryl and sustained-release melatonin to negate it.  When he switched to Intuniv, we were able to phase out the Benadryl and melatonin.  Due to the different release, it's not as activating.it does seem to have started around the time i added more guanfacine in the morning.  thank u so much for your reply.  we will be going in for his next dr appt this month and i will ask her about the intuniv.  does it help with tics the same way that guanfacine does?  thats basically the only reason that he needs it.  i really appreciate your help!
my son is 9 years old and currently on 15 mg of adderall xr and 2 mg of guanfacine, 1 mg in the morning and 1 mg at night.  He has been on adderall for about 1 year and does pretty well on it.  we did have to give him 1 mg of guanfacine for tics and within the last 3 months have added the 1 mg in the morning.  he has always had a hard time falling asleep since he has been on stimulants (3 yrs) so we were giving him melatonin at night.  i found out last week that he has been having nightmares since about sept/oct.  i lowered the dose of melatonin and after a few days they didn't go away so i lowered it even more.  he was taking about 3/4 of a mg in the end.  he was still having nightmares so i said we would see how he could sleep without the melatonin to see if thats why he was having nightmares.  i know sometimes if the dose is too high ppl have bad dreams.  he hasn't taken melatonin now for 3 days.  the first 2 nights he didnt have a nightmare but he said he did last night.  he is having dreams about monsters getting him or hurting or killing him.  sometimes they are the same ones and some are new. he has had a night light since sept and he is pretty scared to go sleep.  anyone heard of these meds causing nightmares or a risidual effect from melatonin or melatonin taking a while to get out of your system? any suggestions or help, i don't know what to do next.  thank u!