Thanks all of you for your sharing, having a quite time is a great idea, I will try it on my son. ��
Btw, did any of you try iLs pillow? My son's OT recommend it when he heard that my son skip his nap when he was 22m old. He doesn't like to use it much at that time due to his hypersensitivity to sound, but now he like it. Even though it doesn't help him to fall asleep and have nap, it does help him to stay clam and reduce his nightmares in the midnight.
Mana, may be you can check it out,
http://www.integratedlistening.com/dreampad/

For the day my son does nap, he always wake up at the midnight and said he want to go out to play and then cry so hard. It makes me prefer him to skip his naps. ��