The warlock's One with Shadows eldritch invocation presents an interesting opportunity: it gives you invisibility without requiring concentration. Specifically (PHB, p. 111):
One with Shadows
Prerequisite: 5th level
When you are in an area of dim light or darkness, you can use your action to become invisible until you move or take an action or a reaction.
Unlike the invisibility spell, this would not necessarily end if the warlock became unconscious. However, the wording that says that this spell ends if you "move or take an action or a reaction" seems to imply that this invisibility is usually intended to last for a very short duration.
But it occurred to me that outside of combat, people often don't do much that technically requires an action, especially if they are at rest. And at other times, it has been indicated that "moving" (for the purpose of magical triggers) refers to moving in the sense of spending movement to change your location on a 2D grid (not becoming prone, or standing up from prone).
So I was wondering: could a warlock use an action to Hide1, then use the One with Shadows invocation to become invisible, then simply lie down and go to sleep for 8 hours (for a long rest), while remaining invisible (and likely hidden)?
Put another way: is there some action, reaction, or move required during a long rest?
1 I included the part about Hiding because according to the rules as written, an unhidden creature that is invisible is still apparent to creatures around it (it can't be seen, but they know where it is). So I wanted to include the hiding part to avoid that argument. And I did so beforehand, because using the Hide action while invisible would break the invisibility.