asthma
"Perscibed this to help with asthma flaring up at night, but now I use it to control my exercise-induced asthma. Take this 2 hours before exercise, it's like magic. Now I walk, jog, even run 2+ miles a day, and for someone who couldn't even walk for an extended time without their asthma flaring, that's a big deal. When I took this near bedtime, and only near bedtime, I experienced weird/vivd dreams. I actually enjoyed it, but the experience may be much more scary for others, beware taking near bedtime if you're concerned. Also, I've been feeling depressed and irritated often. I've had dark  thoughts, I'm not sure it's from Montelukast or from outside factors. I've had these feelings before taking it, it's just more often now."