One of the earliest usages of "at night" is from Chaucer 's works. However, there is one earlier usage listed in OED. The following are the definition of at night and earliest examples from OED: at night: at nightfall, in the evening or night; during the hours of darkness. Freq. designating a specified time.
Do you think '2 o'clock in the morning' might somehow actually mean '2 o'clock in the afternoon', as that's the only alternative? I suppose I can see your point if someone says '11 o'clock at night' for 11pm, but again, unless you're above the arctic circle, the distinction with '11 o'clock in the morning', or any normal representation of 11am, is surely clear.
There is no rule that I know of that forbids this usage, but I would strongly advise using the one-word spelling variant: " nighttime " Finally, the Ngram chart below shows the popularity of the following expressions in the English corpus: a) day and night time, b) day and nighttime, c) day and night, and d) night and day between 1930 and 2022.
What can I say about a thing happened at night? Someone stole my phone at night. OR Someone stole my phone in the night. Which one is right to say?
I thought the day ran from sunrise to sunset, just as the night runs from sunset to sunrise. There are black-and-white speed limit signs that post twin speed limits, one for day that's black on white and one for night that's white on black.
What a person would be called who loves the night or staying up at night? In both senses, like the young generation with their smartphones, and someone who just loves staying up late at night.