The soggy heat? Or the soul-shredding thought of another 83 days debating debates until the referendum?
Whatever caused the opposition to flag at FMQs, it had the reverse effect on Alex Salmond, who romped rampant through proceedings, squishing and splatting rivals like summer bugs. A windscreen would have shown more mercy.
Labour's Johann Lamont, whose political Sat Nav finds a wrong turn each week, had tootled up with quotes from BMA boss Dr Brian Keighley, who reckons the NHS is in "crisis management".
Mr Lamont gravely seconded the diagnosis. But Mr Salmond was fully prepped.
Public satisfaction with the NHS is 61% compared to 45% when she was a minister, he told her. Ms Lamont ground her gears and tried another cul-de-sac: what was his plan for the NHS?
At which, Mr Salmond simply hit the throttle.
Unlike Labour, fund it "to the maximum degree". Ms Lamont went into a ghastly skid.
"He wants to make this a cheap political debate," she screeched, to great SNP laughter.
"Settle down!" honked the Presiding Officer.
The last dignified exit behind her, Ms Lamont claimed the SNP was "not interested in the NHS".
Tory Ruth Davidson, in an orange and blue outfit that caused solar flares on the in-house TVs, listed thinktanks critical of the FM's plans, including the Office of Budget Responsibility.
"Right from the start I believe that the Tories have used the OBR not just as part of government, but as part of the Conservative Party," said Mr Salmond, his theatrical frown a dead giveaway.
"I'm quoting directly from Alistair Darling!" he then revealed, suggesting even the leader of Better Together files the OBR under mince.
The final question went to Murdo Fraser, from whom Ms Davidson burgles her best ideas, and who this week backed a federal UK.
The FM had no doubt that he would support independence soon too - Federal Fraser shook his head unconvincingly - "but I'm confident the independence campaign will survive that endorsement and go on to victory".
Mr Salmond has had a bumpy few weeks at FMQs. But as he departed for the summer, he left his foes looking flatter than roadkill.