Many AD/HD medications have side effects which include decreased appetite and/or insomnia. I'm an adult who takes Ritalin and I have those two side effects as well. They are the most common side effects to the AD/HD medications.

TGG

my son has the same problems and has had for 5+ years, as for his sleeping we consulted his doctor who perscribed he Melatonin wich is a natural drug that your body producess to tell you you are tired, my son was only allowed to be on this drug for 3 months to kick start his natural drug, which has helped a little I can say he does fall asleep around 11pm rather than 2-3am.
My son has an eating disorder which is linked to depression, and he is very underweight he is 10 years old and only ways 27kg, the only thing I can advice from experience is try not to react to the eating as this feeds the attention they want and get him to drink milk shakes and cheese and try minadex tonic to add vitamins and it can help to bring the appetite back. Also remember sleep deprevation has a very bad affect on us all especially us mums so see your doctor. Good luck and hope my advice helps.

Melatonin is very good at getting my 9 year old 57 lb. son to sleep at night. He doesn't sleep perfectly but is not up all night and goes down in about 20-30 minutes versus 3-4 hours. I use KAL brand disolvable Lozenges 5 mg. which is breakble adn approved by our physchiatrist and pediatritian.

The problem with the medication for adhd is that it surpresses appetite but from experience i have found that as they grow and get used to the medication, their appetites return. If issues are made at meal times he may use this as a way of gaining attention. And with the sleeping i have the same problem. Mikey tends to settle when he listens to his radio, it's not the best way of solving it but it works.