One of the missions requires that it be night, but I can't sleep. How do I make it nighttime? If I need to wait, how long? And is there really nothing I can do other than waiting several hours?
There is a story mission at the beginning of the game that requires it to be night. It will automatically become night time when you start this mission, so don't worry about that.
There are a couple of wasteland missions later in the game that also require it to be night. These do not advance time automatically, so it will need to be night before you go to these mission locations. It seems that it is either dawn or dusk when you start the game, and it is about an hour from dawn until dusk. So the worst case scenario is you turn on the game, it is dawn, and you wait an hour.
Of course, the ideal case is that you turn on the game, and it is dusk, so that you do not have to wait at all. Unfortunately, I haven't figured out if there is any rhyme or reason to which it starts as. At first I thought it was based on the actual time of day when you start the game, but if it is, it doesn't use the system clock, so there is no way to manipulate it. (I changed the time on the PS4 from 14:30 to 23:30, but it still started as dawn.) It doesn't appear to be strictly random, as I restarted it multiple times in a row, and it was always dawn. My last guess is that it's based on the time of day when you quit the game, so it might advance to night if it is more than halfway through the day, or something like that. I'll test this theory and edit if I figure out anything definitively.
On this discussion board a steam officer says this: "It goes to the correct time of day / night automatically when you start the mission."