Japanese Emperor Hirohito came back from the brink of death, and his doctors on Wednesday reported significant improvement in his condition.

The 87-year-old emperor's blood pressure fell sharply into the danger zone on Tuesday, but he had a peaceful night's sleep and was conscious on Wednesday, palace officials said."The emperor slept well last night," Palace spokesman Kenji Maeda said. "This helped him stabilize."

"The emperor's condition is stable," said Akira Takagi, Hirohito's chief doctor.

There has been no official explanation of what is wrong with the world's longest-reigning monarch, though there has been widespread speculation in the Japanese media that Hirohito is suffering from inoperable cancer of the pancreas.

The emperor's heart and kidneys had apparently shown no bad effects after he suffered the worst crisis of his eight-week fight for life on Tuesday, Maeda told reporters.