Can someone explain the 2 hour thing?

[jojoisamum]

I have read it mentioned a few times but no explanation!

Erm, no idea really. But I do know when my baby was about six months or so, that was how long she could keep awake in the day before needing to be put down for a nap. Is that what you mean?

PuppyMonkey is correct, it is the gap between awake/nap time.

Better watch for sleep clues: yawn, slow blink and in generally they get a wee bit grumpy and try to get them in cot straight away. It is harder to settle them if you missed the clues.

Good luck!