TOKYO (AP) — Japan’s 86-year-old former Emperor Akihito fainted at his residence though he regained strength after a good night’s sleep, the palace said Thursday.

Akihito underwent an MRI of his brain that showed no clinical condition that could cause a fall, but doctors recommended close monitoring of his health for a while, according to the Imperial Household Agency.

Akihito abdicated last April and now holds the title of Emperor Emeritus. His wife Michiko was at his side when Akihito fainted Wednesday at the Imperial Palace and she called the palace doctor, palace officials said.

The doctors found Akihito still unconscious and sounding as if he was snoring. He regained consciousness and went to bed but woke up normally Thursday morning, officials said.

The popular former emperor had symptoms of cerebral anemia, or low red blood cell count, last July, when he briefly had difficulty standing, officials said.

Akihito reigned for 30 years and gained widespread respect and sympathy as a politically neutral symbol of the nation and for his dedication to pacifism.

Akihito’s son Naruhito ascended to the Chrysanthemum Throne on May 1.