I love your discussions and polls!
I've been too sleepy for sex many times. I have spells where I'm too exhausted for much of anything, including sex. I think our bodies respond by turning off sexual response, mental and physical. Once you've rested, you'll be back. I wouldn't worry about it unless it goes on for a long period of time (only you know how long is unusual). If that's the case, it is time to see the doc to make sure there isn't some underlying cause.