I'm 120 pounds and take an adderall xr 30mg in the morning. is it okay to take a 50mg dramamine (dimenhydrinate) at around 11pm to help me sleep?

Should be ok: Can't think of any problems--there r better sleep aids than dramamine (dimenhydrinate) but if u r happy with it no problem.

Adderall (dextroamphetamine and racemic amphetamine): As long as these are prescribed and u have no residual effect the following morning from dramamine, (dimenhydrinate) should be ok.

Full Day Dosing: You will be better off if your prescriber gives you full-day dosing for your ADHD. Adderall (dextroamphetamine and racemic amphetamine) XR lasts no longer than 12-hours and if an adult does not have a late afternoon dose of this or similar meds, they often experience a kick-back effect and have a disturbance of sleep. The late afternoon dose of short acting stimulant should drop off just before bedtime and you will sleep like a rock.

Consider alternative: If you are experiencing difficulty getting to sleep after taking Adderall XR, consider a problem with rebound to an over tired state. Among alternatives would be Vyvanse (lisdexamfetamine) which can last up to 15 hours or consider Provigil or Nuvigil which generally do not negatively affect sleep.