Sleeping later than intended in the morning; oversleeping (often expressed as 'to oversleep').
毎朝朝寝坊して、仕事に遅れそうになる。
I oversleep every morning and almost get late for work.
休日は朝寝坊するのが楽しみだ。
On days off I enjoy sleeping in.
朝寝坊が直らなくて困っている。
I can't break the habit of oversleeping and it's a problem.
今日も朝寝坊してしまった。
I overslept again today.
A person who often sleeps late; a late riser (someone bad at getting up in the morning).
うちの弟は朝寝坊で、いつも朝ごはんを食べない。
My younger brother is a late riser and always skips breakfast.
彼は学生時代からの朝寝坊だ。
He's been a late riser since his school days.
『朝寝坊なんです』と彼女は笑って言った。
"I'm a late riser," she said with a laugh.