Today: 60 goodnight quotes to send someone to sleep with a smile
Night refers to the time after sunset. Accordingly, it can be both morning and night (this being pretty much the definition of the small hours). Midnight refers to exactly 0000/2400 hours, and the time just around it. 2301 is not midnight. "Good night" does not mean "have a good sleep".
After brushing your teeth, putting on PJs and shutting off the lights, the only thing left to do is send a final goodnight text to someone special, reminding them that they’re the last thing you think ...
- The origin of "at night" to indicate a point of time and the usage of prepositions "in" and"at" In olden times, when the time expression "at night" was originated, night might have been thought as a point of time in the day because there wasn't any activity going on and people were sleeping that time unlike daytime.
The expression by night is typically used to contrast someone's nighttime activities to their daytime activities, especially when the nighttime activities are unusual or unexpected. You will see it very frequently in the construction X by day, Y by night. Some examples: ...treated it like a greasy spoon by day and a hotel by night I mean, if it's -- if it's somebody that is -- is living as a ...
The spoken use of "night" as an informal, familiar version of "good night" (wishing one a restful sleep) is common, but I'm not sure what the proper written equivalent is - if there is one.
Adding Time brings the two into a comparison of time periods. Saying just Day and Night compares the non-time/instantaneous status; light and dark, up and down, inside and outside. This is the purpose of the usage, not a time period.