Levocetirizine
"Took this for allergies and to help me sleep.  I had the best sleep I've had in years, BUT I was so groggy and hazy during the day that I stopped taking it after 2 nights.  This certainly works for allergies (no more sneezing or itchy-watery eyes), but I wouldn't take it if you have small children or a day job.  I had such a hard time keeping my eyes open at work."