Rop tussu m’athair, rob mé do mac-su; rop tussu lem-sa, rob misse lat-su.
Both waking and sleeping my presence my light.
I read this as a poetic restatement of line #3. But by distinguishing waking from sleeping it adds a new dimension to Christ consciousness.

I have frequently experienced a better night’s sleep after having prayed Compline just before bed. Did the prayers affect my dreams or can one say “night time consciousness”? The scriptures contain several references to God ministering to us in our sleep. This line implies that there is a reality to God’s presence whether we are conscious of it or not.
God is still God whether we perceive him or not.
This idea may seem overly obvious, but: God is still God whether we perceive him or not. You might be saying to yourself, “Ummm…yeah! Of course he is! A mushroom is still a mushroom whether I see it or not. Thunder claps are still loud even if I can’t hear it – and everyone knows that if a tree falls in the forest with no one around, it still makes noise…duh!”
It turns out that some of the world’s smartest people are not so convinced. There is the concept known as “Observer Effect” in physics which states that “the mere observation of a phenomenon inevitably changes that phenomenon.” The idea is mostly limited to the realm of quantum physics, sub-atomic particles and the like. But if true, the reality is that a thing can change just because we perceive it.

There’s an intuitive form of this. For example, as a child I indulged in the fantasy that everyone except me was really a monster or an alien, but in the instant just before I looked at them, their appearance would change to that of a normal human. I would entertain myself from time to time by trying to “catch” them. I don’t think I’m the only one.
In the 1999 comedy film, “Mystery Men”, one of the “wanna-be” super heroes was called “Invisible Boy”. He could become invisible…but only when no one was looking at him. The usefulness of such a power is dubious at best, but it makes for great comedy.

Will anything last?
There’s something in us that resists the idea that everything is relative. I’m disturbed by the thought that just looking at something could change it. It’s unsettling. We don’t know if the ground beneath us could turn to quicksand in an instant. We don’t know when fire might fall from the sky instead of rain. There is no government that will last, human construct that will endure or edifice that will go unchanged by time, weather or man…
…but God never changes. Whether I’m awake or asleep, He is there. Whether I can see him, hear him or feel him, He is there. He is the same yesterday, today and tomorrow and my perception of Him does not change who He is…waking or sleeping…my presence. My light.