I take 15mg extended release adderall for adhd and sometimes i can't fall asleep. i'm 130 lbs should i take 5 or 10mg of melatonin?

Melatonin - maybe no: Adderall will cause issues with insomnia but Melatonin may not be up to the task of counteracting this side effect and could actually worsen insomnia. Talk to a neurologist or psychiatrist to find out the best treatment option. Insomnia is a complex issue and it is important reversible causes have been ruled out and you have a treatment that will work well for you based on all of your medical hx.