From the question, it appears that you are experiencing memory problems and hallucinations after taking Concerta (Methylphenidate). Concerta is also marketed as Ritalin and is used to treat attention deficit hyperactivity disorder, narcolepsy, and other developmental disorders. It functions by increasing the levels of dopamine and norepinephrine in the brain by prevent their re-uptake in neurotransmitter junctions. Concerta has a number of side effects, some of which affect the brain and are serious.
Although memory problems are not a known side effect of Concerta, patients who experience hallucinations should seek immediate medical attention from their primary care physician, psychiatrist, or the primary prescriber of the medication as it could be a sign of an underlying psychiatric disorder.
Your reported history of memory disturbances, decreased concentration, bizarre lucid dreams, and decreased sleep is suspicious for an underlying psychiatric disorder such as bipolar disorder or possibly schizophrenia. You should be evaluated by your primary care physician, psychiatrist, or primary prescriber of the Concerta and especially if you have a family history of psychiatric disorders such as bipolar disorder or schizophrenia.