Translation guide
Expresses the idea of 'all the time', 'continuously', or 'around the clock'. Japanese uses set phrases and adverbs rather than a direct translation of 'day and night'.
To say that something happens without stopping, 24 hours a day.
To compare or contrast daytime and nighttime, not necessarily continuous action.
Simple noun phrase meaning 'day and night' as two distinct periods. Use when contrasting them.
昼と夜では気温が大きく違う。
The temperature differs greatly between day and night.
English 'day and night' often means 'all the time'. Translating it literally as 昼と夜 (day and night) in such contexts sounds unnatural. Use 日夜 or 昼も夜も instead.
He works day and night.
Literally 'both day and night', used adverbially to mean 'all the time'. Slightly more conversational than 日夜.
彼女は昼も夜も勉強している。
She studies day and night.
Means 'regardless of day or night', 'around the clock'. Often used in formal or written contexts.
この店は昼夜を問わず営業している。
This shop is open day and night.
Literally 'four six hours all the time' (4×6=24), meaning 'around the clock'. Somewhat old-fashioned or emphatic.
彼は四六時中ゲームをしている。
He plays games day and night.
More formal or technical way to say 'daytime and nighttime'. Used in weather forecasts, schedules, etc.
昼間と夜間の温度差に注意してください。
Please be careful of the temperature difference between day and night.