Where did the long naps go?

Kendra

My daughter [2 mths] has stopped taking naps longer than 40 minutes. Our pediatrician recommended leaving her in her crib to cry for up to 10 minutes to get her to go back to sleep but that hasn't worked. Any tips for how to get a longer nap out of her? She sleeps for longer stretches overnight (thank goodness) but we cant get good naps during the day.