I don't have a meter (that I know of) in the actual sense, but I call these days "low battery mode" and yes they do happen mostly if the couple days prior have been eventful in one way or another - whether stressful or blissful, that doesn't even matter. On paticularily bad "low battery" days, I don't even feel hunger/thirst and have to force myself to eat and drink the bare minimum. Literally everyhing is a slog for a while then, even things that I normally enjoy. It usually takes a day or two to get better on its own.

....and yes, trying to explain these things to someone who has never experienced the issue firsthand is very difficult. People usually assume I'm just feeling a bit down and need cheering up, not understanding that the things that normally would cheer me up do not have ANY effect at the moment, and that I'm not "feeling down" but don't feel anything at all.

Sadly I haven't found a good way to cope with the issue except for waiting it out until it goes away.

I’m not diagnosed but I “feel you” lol. I never really had a name for it aside from just hitting my limit. There’s no amount of excitement, argumentativeness, sorrow, etc that reaches me after that. It’s like being physically or mentally exhausted but for your emotions. Its never really concerned me though because what am I supposed to do about it?

Overall it’s a similar response to my social battery. It just wears down to the point where I’ll withdrawal, and if someone tries to push me further I get very snippy and will eventually just leave the area/situation or go completely gray rock until it ends. As I’ve gotten older I’ve noticed I’ve built in escape hatches for myself and have no qualms about just walking out of emotion-ridden situations or even the middle of conversations. You will never see me without control over my own transportation to get home for more than about 30 minutes, and that’s only in emergencies.

I’ve never really planned my day around it though, as I’ve already built my life around it. I’m reclusive and analytical by nature and any type of strong emotion is usually a bit much for me. I hate sappy movies and songs, I usually refuse to participate in arguments after a certain level of heat is hit, and I find excessive excitement grating to my nerves. My family growing up was always very “extra” to me so they’ve learned they only get a few hours during the holidays before I do the ol’ Midwest knee-slap and hit the road.

Now the only time I hit my limit is usually during arguments where I am disinclined to leave (like at home with a spouse). Then I just end up looking like a psychopath because I’ll suddenly just kind of shut down and just go numb. My husband says he finds it very unnerving but it’s a pretty rare occurrence.

Emotions take energy, and we all seem to have a limited amount of energy to expend throughout the day, week, or month. But it also seems like it can be practiced and you can build emotional endurance, utilizing different tools that mental health experts have developed, to help extend your limits and prevent you sometimes from feeling completely drained. It does take practice! And some days you'll be affected by things that are just simply beyond your control, such as unexpected interactions and hormones, etc. I've personally found that medication for anxiety helps me to limit the amount of energy I'm expending on emotions because I'm no longer reacting as strongly to everything and being in a constant state of fight or flight, which allowed me the time and space to build my endurance in a healthier way, but it's going to be different for everyone just due to genetics and environment and lifestyle, etc. What you describe specifically sounds a lot like depression, from my own experiences, but you know yourself best. Have you been able to speak with any mental health professionals about your concerns?

I have always thought of myself as a battery, and any interaction drains the battery. Big interaction of course take more juice than small things do. Sleeping and interests help to put some juice back into the battery, but if it's been a big drain day/week I'm slow and my mind is almost sludgy until I can get some alone down time to recharge.

Edit - For me, upbeat/jammy music helps with the recharge or at least lowers the drain rate. Sad or emotional music uses juice though so I have skipped tunes before that I know are going to burn some of the reserve I can't afford to allocate to them at that time.

I would say this is likely a regular human thing that we just don't understand. I get like this too, I think it has to do with overstimulation which is mind boggling to me because I am usually bursting with energy.