Fiorecet helps my mind work better, but is it actually the caffeine?

After about 30-60 minutes, the drug reaches peak concentration. The effects of clear thinking and relaxation only last for about 4 hours though, then I feel fragmented again. There are some residual effects for an additional couple of hours in terms of mood regulation, but my cohesiveness drops off. However, I have read the butalbital has a half-life of 35 hours and caffeine has a half-life of only 3 hours; this suggests that the caffeine is what is causing the primary functional benefits. If this is true, then taking Xanax really isn't going to get my brain to be functional even if it relaxes me. I often substitute/supplement with excedrin migraine, where it's basically caffeine affecting me. If this is true, then I might need a stimulant type medication (cohesiveness) with a mild sedative (anxiety); what long-acting stimulant type medications (think ADD meds) are out there, and which are easiest on the body?