Tim Bowen sheds some light on the origins and definition of the phrase to feel out of sorts.
A common answer to the question ‘How are you today?’ is ‘I’m feeling a bit out of sorts’. You can also say ‘You look a bit out of sorts today’. This means that you don’t feel right. You are not necessarily ill but you don’t feel 100% healthy or you don’t feel your normal self.
Unusually, this expression is believed to have its origin in the printing trade. Before the days of computers and desk-top printing, all printing was done by hand and was a very laborious process. Sorts were the small pieces of type printers needed to make up a font. With a full supply of sorts printers could work steadily but if they ran out of sorts they had to stop working. As many printers were paid according to the number of pages they could produce per day, being out of sorts usually made them angry or bad-tempered.