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.
