The title means "Sick Dreams".
When Harrow calls Simon after the case is solved, Simon ends the call by saying "Aye, aye Captain Bligh!" This is a reference to Captain William Bligh, most famously of the USS Bounty. He was a formidable and much maligned officer in the British Royal Navy. One of Ioan Gruffudd's most memorable roles is as the titular naval officer aboard the HMS Indefatigable in the television series Horatio Hornblower