On a 5am wake-up what is their schedule? What time are they going to bed? Harrison only sleeps max 10.5 hours, so early to bed early to rise!
When Harrison does 5.30am, I generally keep him on track, 5am and I give him a 30 minute catnap as early as I can, then try and get him to nap again as close to "normal" time of 12.30pm as possible to keep bedtime the same.