Sleep Begets Sleep

I read once that for little ones sleep begets sleep.  That has seemed to be true for Little Britches for sure, but right about the time the time changed we got off and have not really gotten back on.  She has had multiple days this week where she has talked and played in her crib for hours without napping when I just minutes before she was barely able to keep her eyes open.  Advice?  Help?  Words of Wisdom?  I am open to suggestions!