Admitting Brain Slumps

I'm in a specific period right now where I honestly don't feel the ability nor patience to sit through a 3.5 hour interview and create a meaningful (to me, at least) response and/or critique of its assertions. I'm not currently in a place (mental, spiritual, intellectual, emotional, nor geographical) that I feel I could offer my best thoughts on something which is probably requiring me to respond at or near the top of my game, and I don't want to fake it.

So it's on my "to do" list for whenever this changes (weeks or months, not years).