The NGram is very persuasive for the usage of "at nighttime" but I concur with Brian Fink that hyphenation is dying in favor of two-term utilization (see what I did there?) and I believe it is a large slip-up. Hyphens can immediate and associate the meaning of a phrase which https://aredogfleaszoonotic35678.tblogz.com/how-much-you-need-to-expect-you-ll-pay-for-a-good-canine-rest-support-49790236