While making a Battle Smith Rock Gnome, I came to a similar question to this one about the Steel Defender, but saw it in another light; Though it is a construct, there is nothing in the stat block or artificer entry that states it does not require rest. While this is also true in the Monodrone entry, I do know that the warforged entry does specifically state that they have an ability called Sentry's Rest requiring them to effectively "sleep" for 6 hours.
As such, I was wondering if such constructs as Steel Defenders would require rest, or if one could combine the following two features to make an effective night watchman?
Vigilant. The defender can't be surprised.
Steel Defender (Artificer entry) [...] If you are incapacitated, the defender can take any action of its choice, not just Dodge.