marcbra Hi marcbra, welcome to the forums. 🙂
What are you taking Vyvanse for? ADHD, narcolepsy, etc?
Modafinil has been shown to reduce symptoms of ADHD but it may not work for everyone. Stimulants like amphetamine (Vyvanse) are still the most effective for ADHD.
Modafinil's mechanism of action is rather complex and it affects neurotransmitters like dopamine, orexin, noradrenaline, and histamine to name a few.
In contrast, stimulants typically affect just dopamine and noradrenaline, and to a lesser extent, serotonin.
Maybe increasing the dose to 200 mg would help but it will also increase the side effects.
Regarding 'finding the right dose' with Vyvanse, if I were you I'd ask my doctor to prescribe instant release (IR) dextroamphetamine along with Vyvanse. Vyvanse is basically extended-release dextroamphetamine so they're not contradicted.
This treatment option is not uncommon. The tablets come in 5 mg each so it's much easier to titrate the IR dextroamphetamine dose until the appropriate response is achieved.