My 9-month DS usually sleeps for around 3 hours in the daytime, 1 hour naps around 8.30, 12.30 and 4.30, or thereabouts. The last couple of days his 'naps' have been longer so that he's having about 5 hours during the day. He hasn't had any less overnight sleep (approx 7.30pm to 6.30am, with a few, short wakings overnight for milk as we're co-sleeping), and he seems perfectly lively during the day, not lethargic, playing happily etc. Is this a developmental thing? Is it normal? I know some babies this age struggle to nap at all, so I'm aware it varies a lot, but come reassure me that some other babies are like this.