The opposite of euphoria, since you ask. I normally have the same delusion as Dr Sheldon Cooper: that my mood floats effortlessly, calm and serene, over life's fretful trivialities. Right!
Yesterday afternoon I took Clare's car for a short spin to charge the battery in these freezing times. Mid-afternoon today, Clare asked where the keys were. I looked in the only places I could conceivably have left them (the shelf and her handbag): they weren't there. The trouble is that putting keys down is an automatic act: it leaves no memory-trace.
So now I was seriously worried. I searched high and low, and racked my brains for ever more unlikely scenarios as to where the wretched things might have ended up. My spirits sank like a deflating balloon - we have no other key: what do you do when you have a locked car on your driveway and no key? Call in some kind of car-thief-capable locksmith?
My depression lasted for some hours until Clare searched her handbag properly and found the keys tucked away in a corner.
My emotional state instantaneously resumed that normal state of equanimity I mistakenly believe I always exhibit. Although just for a moment I experienced an unaccustomed feeling, best described as ... relief?