Had 1/2 mug of coffee yesterday evening, around 6:30-7:00 PM, don't know if that was it, as I usually will not drink coffee after noon, but had problems sleeping. My tinnitus (ringing in the ear(s) has been louder than usual in one ear (could be the caffeine), so that probably didn't help, though after having it for years now, I've grown used to it (or just tolerant of it).