> I'd like to see how I react to both together, but hesitant given my poor reaction to Adderall. When I was younger I remember preferring Ritalin over Adderall.
I always advise against poly-pharmacy if possible. Particularly when dealing with powerful stimulants for which the mechanism of action isn't fully understood (Modafinil).
Interestingly, Modafinil might somewhat antagonize the Adderall due to an interaction between their mechanisms of action. Modafinil's MOA is partially due to dopamine reuptake inhibition (similar to Ritalin), but Adderall relies largely on being taken in to the presynaptic terminals and forcing dopamine out. By inhibiting dopamine uptake, Modafinil can (theoretically) decrease the amount of Adderall taken in to the terminal as well as the amount of dopamine available in the terminal for release. We've seen this in a few studies where Modafinil can actually reduce the neurotoxic effects of Adderall, likely due to this antagonizing of Adderall's core MOA.
The magnitude of this effect at therapeutic dosages is unknown, but it's possible and even likely that the combination would be distinctly different than what you might expect a combination of the two drugs to feel like.
> EDIT: Adding to the throwaway comment below, the long halflife of Modafinil is true, especially when trying to sleep. For me, after months of 3-4 days on a week, there seemed to be no long term issues with this, where days I had taken Modafinil I only slept 3-4 hours.
It's expected that your body would adapt somewhat to sleeping on the medication, but that doesn't mean that you were getting quality sleep. Humans are notoriously bad at judging sleep quality, for one, but more importantly here: You were taking a wakefulness-promoting agent, which would have covered any subjective feelings of poor sleep. My concerns with Modafinil stem more from potential long-term implications of interrupting sleep, particularly when the traditional signs of poor sleep (daily fatigue and sleepiness) are then obscured by the drug itself, leading to a false sense of restedness.
However, we can begin to infer poor sleep quality by other, indirect markets, such as:
> I definitely had issues with alcohol and Modafinil, where at my weight (220lbs) I could normally drink 3-4 pints to reach 'buzzed' status, this seemed to happen at 1-2 pints. This trend stayed consistent - and proper 'drunk' came much quicker. This had the effect of limiting my drinking, to the point where I would switch to light beers and stop drinking after 1-2.
Getting subjectively incapacitated from a lower number of beers could, theoretically, be indicative of a subtle sleep-deprived state, for example.
Again, much of this is just semi-educated conjecture, but given the importance of sleep to long-term health I'm wary of these stimulants with long half-lives.