I think, it means mistake or a flaw and the բեխալատ would be the opposite of flaw, I mean flawless. I'm just going with the sentence structure and the Arabic word Khalat means mistake or a flaw, maybe that's where the origin is. I hope this helps. I believe the babies flaw is not falling sleep. The last sentence which says that you have one flaw, you don't sleep and stay awake.