That's probably an appropriate use of kava. I wouldn't get kava tea in teabags, it probably isn't very strong. Look for instant drink mix, extract, or tincture.

Kava's effects are like a mild benzodiazepine. It's a relaxing, mild sedative. Erowid is the authoritative source for the effects of these kinds of things, though most of the people there are probably doing higher doses than you want to do while coding. http://www.erowid.org/experiences/subs/exp_Kava.shtml