K.W.
My 22 month old daughter usually takes naps from 3 to 5 hours long, which gives me enough time to clean and take a short nap! I love it! And she still sleeps great through the night, usually from about 8 or 9 at night till 8 or 9 in the morning. I think if they are sleeping that long, it's because they need that much sleep and there's no need to worry about it.