where is the 'at'?
Turkish doesn't use it in this expression. :)
You can use 'geceleyin' instead of 'gece'. That depends on your choice.
As well as "akşamleyin", "öglenleyin" and "sabahleyin". I think it's just different for times of day.
In fact there a few more exceptions such as 'kışın' and 'yazın', but not a lot.