I laughed at a joke and felt the delay before the laugh reached me

Dear Delyara, My husband said something funny at dinner and I did laugh, but a tiny second too late. Long enough for me to notice that I had heard the joke before I had emotionally arrived at it. That tiny delay made me feel unexpectedly sad. Because that is what tiredness has become for me sometimes. Not dramatic collapse. Delay. A lag between life happening and my real self catching up enough to participate cleanly in it. I can still do the motions. I can still answer, respond, laugh, help. But something in me arrives half a beat behind. I don’t think people see that kind of exhaustion. I barely name it myself.