I have slept the better part of this day so far, and part of it honestly feels like a Benadryl hangover. I haven't taken it much lately, and sometimes I'll feel a prolonged or delayed reaction to it. I'm eating yummy turkey and stuffing leftovers and drinking caffeinated beverages to get the blood moving again. I don't feel "sick", but I do think it's a combination allergies and light cold. The second night and morning should tell the tale.