expression
in spring one sleeps a sleep that knows no dawn; in spring one sleeps like a log
Proverb meaning that spring mornings are so comfortable one oversleeps without noticing the dawn. Originates from a poem by Meng Haoran.
春眠暁を覚えずで、今朝も寝坊してしまった。
As they say, in spring one sleeps a sleep that knows no dawn—I overslept again this morning.
From a line in a poem by the Tang dynasty poet Meng Haoran (孟浩然). The phrase is used as a proverb in Japanese.