It's part of my treatment regimen for sleep apnea, which includes a CPAP breathing assist device. That's usually enough to reduce the low energy and daytime sleepiness that come with sleep apnea. When it isn't, modafinil works very well. So I was prescribed both the CPAP assist and modafinil after a brief sleep study disclosed sleep apnea. The two other on-label uses for modafinil (IIRC) are for narcolepsy and daytime sleepiness due to shift work. Being prescribed for an on-label use is often important for insurance coverage.

Honestly, I just went to my family doctor and asked for it.

I took a look at the symptoms for Shift Work Sleep Disorder, decided that I was a close match for that cluster of symptoms and took my story to the doc.

Modafinil is not really prone to abuse. It isn't a euphoric, so using too much isn't going to give you a "high". Consequently, doctors are more likely to give you a prescription for it. That's not the case for an abused drug like Adderall.

HOWEVER: all drugs have side effects. I think Modafinil is relatively safe but YMMV.