Philippine President Rodrigo Duterte missed several meetings at the Asean summit because he was taking "power naps", the presidential office said on Thursday.
Spokesman Salvador Panelo said the President missed four scheduled events on Wednesday and had "worked late and had only less than three hours of sleep", the BBC reported.
Duterte and other world leaders are in Singapore attending the Association of South East Asian Nations (Asean) meeting.
When asked if he was fully rested, Duterte added that the naps were "still not good enough, but enough to sustain the endurance for the last days".
Panelo also clarified that Duterte's absence had "nothing to do with his health".
The 73-year-old defended his actions, saying: "What's wrong with my nap?"
Duterte has previously missed events at other international summits as well as in the Philippines.
His health has been a constant source of speculation over the year, and he revealed in October that he had a cancer scare.
But Duterte wasn't the only official caught napping at this year's Asean meetings.
A Washington Post columnist captured a picture of South Korean president Moon Jae-in, in which he appeared to be asleep.