In addition to what Dor B said, naps are very important as this is for developmental reasons. Children this age NEED about 10-12 hours of sleep at night. Napping length can very per the child.
1) does she have enough intake? meaning milk and food? If not, they are basically always hungry and starving and not satisfied and cannot sleep. I don't mean feed her like a goldfish, but I've seen many babies that don't intake enough or don't feed well and it's not good.
2) is she gaining weight/growing appropriately? If not, this can cause a problem, it means she is not intaking enough.
3) does she have allergies or digestion problems?
4) is she sick or anything?
5) put her to nap in the SAME place at the SAME time, everyday.
6) put her to nap while she is still awake. A baby/child has a pattern of: awake, eat, play, sleep. After about 2-3 hours of "awake" time, they will get tired. Don't wait for her to tell you if she's tired... YOU put her to nap/sleep at the same time, and have the SAME pre-nap routine everyday. They will get used to it. Kids need routine and knowing what comes next. (7) example: my 20 month old still takes 2 naps a day. Morning at 9:30 and afternoon at 2:30 and he sleeps for 2 hours each. He wakes, I feed him, play, then give him his milk, change his diaper, put on his favorite SHORT DVD or read a book, pick him up, sing him the SAME song, put him down in crib, make room dark, give him his pacifier and stuffed cow he loves to sleep with, walk out of the room and close the door. He is still awake when I put him down, but he falls asleep on his own. I do the same routine at night for bedtime. I've done this SAME routine with him since he was a baby... even through his developmental changes and sleep interruptions I kept it the SAME... and now, he knows when is nap time/sleep time and goes with no protest. He will even tell me when it's time to nap and will sometimes take my hand and lead me to his crib.
8) at your girls age, they still need 2 naps. Keep trying.
9) when babies/kids are over-tired this will actually make them more resistant and they will actually get more "hyper" too sometimes. Or if they are over-stimulated as well. Pre-nap or sleep, I calm things down and make things more mellow. Make sure to allow for a child to "wind-down." Don't rush them off to bed...they have to "transition" too. They need to unwind.
10) Don't just try to get her to nap when she "seems" tired.... by this time it may be too late. Put her down at a certain time. The SAME time everyday.
11) at times of developmental leaps, this can interfere with their sleep. They are changing so much and cognitively as well too. But, through this, keep to the same routine and they will go back to their pattern.
12) each child is different... my firstborn was like your daughter.. but I kept at it, and kept to a routine. She was very spirited, but she would go down. Even now at 5 years old, she will nap after school. She "knows" this is the routine. If she doesn't nap she gets very grumpy and fussy. I know her too well and know she needs a nap. Now, she will even tell me "Mommy I'm going to nap now" and she goes in her room and lies down.
13) with my girl, she is also noise sensitive, more than the normal person. So, I have to keep things quiet for her in order for her to sleep. My boy on the other hand, will nap well despite.
14) if all else fails, there is "co-sleeping." I have done, and still do this too. If my boy wakes up in the middle of the night I pick him up and co-sleep with him. I did this with my first born too. But remember, it's not for everyone, and it will be a "habit" once a child gets used to it. Like any other routine or habit. :)
Hope this helps, I know it's not easy. Keep trying.
Take care,
~Susan
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