Need proof? Just look at his face...
Here's another one just to be sure...
Despite Cameron's hard work and tireless work ethic, sympathy was far evident.
Handily, people were on hand with some helpful advice.
Then there was this brutal assessment of the entire political scene.
And others were simply thinking about his poor family.
Luckily for us there were pictures.
As leaders reconvened for the second day of the European Council summit, Cameron pledged that he would not accept a watered-down agreement which did not meet his demands for change, reports The Press Association.
"I was here until 5 o'clock this morning working through this," he said. "We've made some progress but there is still no deal.
"As I have said, I will only do a deal if we get what Britain needs, so we are going to get back in there, we are going to do some more work and I'll do everything I can."
To be fair, the outpouring of negative sentiment began long before he had even started negotiations.