Curious behavior: Wakefulness from sublingual, somnolence from swallowing (long-term, Modalert)

This is a follow-up to https://www.reddit.com/r/afinil/comments/3fbi61/feeling_sleepy_on_modafinil_effect_inversion/

I've been a regular, long-term (~50mg/day, 250+ days over ~1.5+ years) user of Modalert and it worked like an absolute charm being swallowed down with a cup of water or coffee.

• For the past couple of months however immediately after swallowing a quarter (or half) of a 200mg pill I feel a sudden onslaught of sleepiness. Drinking coffee further exacerbates the sleepiness (however coffee doesn't do so when taken without Modalert.). Staying hydrated helps manage the sleepiness but doesn't eliminate it.

• From last week, I've been dosing sublingual and it's been very effective with wakefulness as long as I completely spit out the mouth-goo after about 15-30 minutes and rinse my mouth with a mouth-wash. If even a little bit of it is swallowed, I feel the familiar sleepiness creeping in.

So the sleepiness appears to be contributed by something that happens to the Modafinil once it's past my esophagus but I haven't been able to figure out a solution.

Would greatly appreciate any thoughts, ideas or experiments anyone may have.

tl;dr: After 1.5 years regular usage, Modalert works different. Swallowing 50mg Modalert causes sleepiness. Sublingual 50mg Modalert causes wakefulness.

update: I'm not entirely certain if my correlation is correct, but one thing I noticed was I'd begun supplementing Bacopa Monnieri (about 750mg at night) sometime during the period the sleepiness started (~3-4 months). The sleepiness however used to kick-in only after I took about 50-100mg Modalert in the morning.

I eliminated the Bacopa about a few weeks back and a few days after that, my Modalert started working perfect again. (I was also on a few other supplements/multivitamins as well during that period and using a different Modalert strip - but my very-biased suspicion is it was Bacopa primarily contributing to the sleepiness.). All's good now though.