Should medical conditions that affected performance be stated in personal/research statement? And how? Condition

I have been suffering from day time sleepiness (9-10 hrs of sleep and still struggle to stay awake), fatigue, memory loss and lack of concentration. The doctor found that I suffocate in my sleep: I stop breathing several times per hour. 

In a few days, I will be undergoing surgery to modify my airway (nose, throat) that, according to the doctor, will completely resolve these problems.

Background

My profile is OK: undergrad valedictorian, scholarships, awards, numerous research experiences and skills. But my condition was exacerbated during the masters and I graduated "B+" instead of continuing my straight "A" performance during undergrad. Also, I felt that I could have performed better in standardized tests (GREs), do more research etc without my condition.

Questions


Should I make this medical condition known in my research/personal statement? I fear the reader might assume that I am not as "able" as completely healthy candidates. Or perhaps there is no benefits at all to bringing this up?
If so, how should I put it to avoid sounding like I am making excuses or whining?
Your potential advisor is interested in (mostly) one thing: your potential as a graduate student. To that end, your personal statement/interviews/etc. should serve to convince him that you will be able to do excellent research. Any issues that could be a potential problem should be noted and addressed.

With that background, do you think this condition could be perceived as affecting your output as a graduate student? From the way you posed it, I would suggest that the answer is "yes". As such, I would mention the condition towards the end of the letter/interview, but I would state  with confidence that past performance has demonstrated that it will not affect output, and you're confident it would not be a problem in the future. Don't dwell; just mention it as you would a disclosure and move on.