If it makes you feel better, I have also done this while mid migraine. Thankfully I realised when I got the confirmation, but I'd already paid for a fairly expensive flight (I booked the month I was in instead of like, in 3 months time), I had to pay a fee change it, and because it had to be with the same flight operator and there wasn't a lot of choice I ended up getting a very expensive taxi to the airport at 4 in the morning.

Executive dysfunction is expensive.