also: まいや
noun, adverb
Used as a noun or adverb to indicate something happens each night. Slightly more formal than 毎晩 (まいばん).
彼は毎夜、日記を書いている。
He writes in his diary every night.
毎夜の習慣として、寝る前に本を読む。
As a nightly habit, I read a book before bed.
毎晩 is more common in everyday speech for 'every night'. 毎夜 is slightly more formal or literary.
Compound of 毎 (every) and 夜 (night). The reading まいよ is the standard on'yomi combination; まいや is an older or alternative reading.