I think Martin is actually morning person he enjoys how peaceful and calm everything is right before the dawn and before the morning rush starts…

During the Scottish safe house period he once went to watch the sunrise and found Jon already up looking at the horizon. They silently watched the first light appearing next to each other.

Then Martin asks Jon how come he’s up already worried that he’s awake because of nightmares and Jon answers to horrified Martin: “Oh I just haven’t went to sleep yet.”