Does anyone have any good tips for stretching out naps? My 7 week-old has started napping for only half an hour at a time (whether she's in the buggy, in my lap, bouncer, cot, whatever) and it's driving me crazy. She then gets tired again after an hour awake. She sleeps pretty well at night (can do a 5-6 hour stretch) so I thought she might nap for longer if I put her in her cot, closed curtains etc - but no such luck. The sling is the only exception but that's not always practical. She's not waking ravenously hungry or anything. I'm sure it's just a phase but I'd like to encourage longer sleeps.