That is not what is supposed to happen.
Prior to my being diagnosed with adult ADHD about 15 years ago, I was a caffeine junkie: coffee, mountain dew, a delightful southern drink called SunDrop which has more caffeine than anything else on the market, I needed the boost in order to concentrate on one thing, as opposed to bouncing around from here to there thinking I was multitasking.
Same thing with all forms of methylphenidrate. Ritalin, Concerta, Vyvanse are all amphetamine based medications and you should be “up” if anything, not sleepy. Adderall also contains dexedrine which ought to be keeping you from falling asleep big-time.
Are you sure you have been diagnosed correctly?
A lot of physicians see depression with ADD/ADHD and will prescribe an anti-depressant to go along with Ritalin but those dosages are ordinarily not strong enough to act like you describe.
Talk to your physician about this, his or her advice will be more valid than anything you read on Fluther.
SRM