If i don't take my concerta on one day, the next day when i take it i feel really drowsy. why is that?

Adaptation: Methylphenadate is a stimulant, and as such combats fatigue. When you take it everyday your body becomes used to the effect, so when you abstain your brain "misses" it.

Concerta s/e?: A few possible reasons: you're also taking lorazepam and Trazodone, which may be sedating, making you drowsy. Concerta is a stimulant which likely counters that s/e. Without the Concerta, the drowsiness may be more noticeable. Concerta dose may be too high and you're having a 'rebound' effect of drowsiness without it. Best to discuss with prescribing doc who knows you best.