Such good reassurance! Thanks all :-)
I really like the idea of awake before 6 being a night feed. Whats all this fuss about starting their day at 7am?! It seems every other mum I know has this down pat. But I refuse to wake him and start the day at that time if he's fast asleep; sleeping baby = sleeping mumma to me!! So I'm perhaps just too selfish to sabotage my morning 'sleep in'?!
By the way I think its not a sunlight or birds issue, his crib is far away from the window. Strange though that he started doing 6-7 hour stretches of sleep on his own at the start of the night, but wont follow that with another 5-6 hrs too... Im just curious as to why honestly, as overall I know I have a reaonably easy baby on my hands.
At that age I didn't wake DS either, but now he's a bit older (9 months), to get him up by 7 just sets up his day so much better - he gets decent morning and afternoon sleeps at good times and settles and sleeps through overnight much better. There's some theories that the time of day sleeps one day affects various rising and napping times the next (not just how well they sleep overnight).
Babies sleep in cycles and have light sleep/ waking throughout the night then go into deeper sleep agan. Your DS may be waking during the 6-7 hours but getting himself back to sleep; but at 5 or 6am he's waking up and not doing so - is there anything you do differently at that time when he wakes that sends him different signals? If you want him to sleep a bit longer in the morning, then you can actually try putting him down earlier at night - it seems counter-intuative but what you're doing is moving the times that he is in lighter/ deeper sleep cycles, so hopefully he is in light sleep/ waking a little earlier and so treats it as still sleep time, not waking time.
I don't think you should change anything if you're ok with what's happening now, obviously, but if you want a different outcome then it's worth trying something different.