Warlock undead sleep 5.5e

The warlock undead rules state that it does not require sleep. Does this mean it doesn’t have to sleep to complete a long rest?

5.5e

That's correct. 

All the other rules about Long Rests still apply, though, including the list of things that interrupt a Long Rest if they happen.

I know it's not exactly the same, but this reminds me of this trait for a Warforged:

Sentry's Rest

You don’t need to sleep, and magic can’t put you to sleep. You can finish a Long Rest in 6 hours if you spend those hours in an inactive, motionless state. During this time, you appear inert but remain conscious.

Quote from Tarod_ >>

I know it's not exactly the same, but this reminds me of this trait for a Warforged:

Sentry's Rest

You don’t need to sleep, and magic can’t put you to sleep. You can finish a Long Rest in 6 hours if you spend those hours in an inactive, motionless state. During this time, you appear inert but remain conscious.

Yeah, the Undead Warlock feature uses the exact same language — you don't need to sleep, and magic can't put you to sleep — but lacks the shortening of the Long Rest duration.

Interestingly it does seem that both would still be vulnerable to being unwillingly put to sleep by non-magical means, like any of the various soporific herbs or drugs in the world.