Someone really spiked Edward the Confessor's wine the night he had a vision sitting in the banquet hall in his palace at Westminster. He claims he saw the Ephesian sleepers turning around(these were dead guys by the way.) Royalty being what it is a messenger was sent to Ephesus (probably laughing all the way) until he got there and it was found that the sleepers had indeed turned from their right side to their left side.
This was taken as a sign of impending disaster.(oh no not another zombie movie). The legend is supposed to be associated with the miseries that Christendom supposedly suffered from the Saracens. The seasonal reference that survives in the St. Swithin's day belief.
The legend goes that various heroes lie asleep, including Charlemagne, Frederick of Barbarossa, William Tell in Switzerland, Brian Boroimhe(Boru)in Ireland and Arthur in Wales. The warning that when the sleepers leave the cave "the belief that certain heroes would issue forth in the hour of their countries direst need.
The French peasants believed in the coming of Napoleon, as the Swiss did in the return of William Tell. During the Russo-Japanese war the peasantry of Russia were confident that General Skobeleff would hasten to Manchuria to lead armies to victory. To this day many Highlanders who remain convinced General Sir Hector Macdonald is not dead, but is awaiting his hour of return. A similar belief attached to James IV who fell at Flodden.
I guess they are still on their left side so we've probably not much to worry about even if they turn back to the right. However, I am not staying around if they get up and walk around,which is why I always keep plenty of gas in my truck. Plus if f the damn thing doesn't start just as William Tell is trying to get an apple on my head. I always have a horse to hop on and You better believe I am hauling ; )
Source: Teutonic Myth and Legend By Donald Mackenzie