I woke up this morning feeling moderately awful, but ignored it on the grounds that it's not too unusual for me to bitterly regret having to drag myself out of bed early in the morning. Half an hour later, after a shower and breakfast, I felt fine, as usually happens in this situation. So I went to work as normal, but felt uuurgh for most of the day. By the end of the day it was clear to me that I'd been right the first time, and should probably have gone straight back to bed.

Tomorrow, if I should feel fine at any point within an hour of getting out of bed, I think I should decide I know better and stay at home regardless :-/