夜(よ)更(ふ)か()し() yofukashiなど nado平(へい)気(き) heikiだ da。 Staying up late is no problem for me. Literal Night-late [etc-など] no-problem [copula-だ]. 平気 is a na-adjective meaning 'nothing doing, no problem, unbothered.' ~など here adds a dismissive 'things like X' nuance — 'staying up late, that sort of thing, is nothing.' Casual boasting register. sleep~など (such as/etc.)
夜(よ)更(ふ)か()し() yofukashiなど nado平(へい)気(き) heikiだ da。 Staying up late is no problem for me. Literal Night-late [etc-など] no-problem [copula-だ]. 平気 is a na-adjective meaning 'nothing doing, no problem, unbothered.' ~など here adds a dismissive 'things like X' nuance — 'staying up late, that sort of thing, is nothing.' Casual boasting register. sleep~など (such as/etc.)