please tell me why dd will only take short naps!

[Chacha23]

Hi,

DD is almost 4 months old, falls asleep like a dream for her naps and for nighttime (I pretty much just put her in her bed, she talks to herself for 10 minutes, and then she's gone).

But if she's in her cot, she naps only last for 45min maximum. I know that she's ready and able to nap for much longer, because when she naps in her bouncer seat (no judging please!) or in her sling, she can sleep for 2-3 hours no problem.

The few times I tried leaving her in her cot when she woke up after 45 min, she just stayed there softly grizzling for another hour, didn't actually fall back to sleep. When I go to pat her and reassure her, it only seems to make her more upset.

Oh and the little monkey won't take a dummy.

Any tips/advice?

oh, and just to explain - it does matter to me that her naps are short, because she also wakes up a lot at night, even though she falls asleep easily. I'm thinking the two issues are probably linked.