昨夜

1. Origins, structure, and basic meaning

• Structure: 昨夜 is read さくや here and means the night immediately before today.
• Basic usage: It describes things such as difficulty sleeping or reading a book last night.

2. Common pitfalls and similar expressions

• Night and day
  • 昨日 refers to yesterday as a day, while 昨夜 specifies the night. 昨夜 does not cover every event that happened during yesterday's daytime.
• Which action it modifies
  • In 昨夜読んだ本, 昨夜 gives the time of reading.