I having been taking Zephrex LA off & on for about 15 years. When my asthma is not being controlled by my meds, Zephrex is the only product that lets me breathe well enough to be able to get to sleep. Yes, it wakes me in the middle of the night, but at least I get some good (though short) sleep. When I first took Zephrex, it was like being on speed; now that I only need to take now & then, I am okay. Will NOT be without it.