So much this. Specifically (for me), it's the simple understanding that I will not be disturbed for as long as I care to focus, so it's worth the "effort" to get in the zone. Which of course means it only takes 30 seconds to get there.
But the screwed up sleep cycles from years and years of this are starting to take their toll, so I've been trying everything I can to replicate that peace of mind during daylight hours. No silver bullet yet.