Struggling to communicate when exhausted

When I get overwhelmed I also experience this kind of dissociation! It's usually anxiety/stress related for me, when things get too much I close off and become numb, detatched, like I'm running on autopilot. I've also gone non-verbal in these scenarios, where I physically can't talk even if I want to or it feels like way too much work to talk or even eat sometimes. I think it might be a protective move by my brain to cope with my anxiety and high stress. It has lessened in recent years because I've learned better, healthier coping mechanisms. I don't know if this is what you're going through or if yours has a different cause but I do think it's worth considering it as a possible subconscious coping mechanism to deal with discomfort and exhaustion

You could have selective mutism which is where you have trouble speaking or even unable to speak from anxiety and overwhelming social situations