Why won't he sleep

Yesterday Iain decided that he was going to cut out his first nap of the day. But because he cut that nap out his pushed his other two naps later. But yesterday he didn't want to go to sleep until 11:30pm. NOTHING that I tried or that Brian tried got him to sleep. We just let him stay awake and play to he was so tired that he basically fell asleep sitting up. Anyone have an ideas to get him to sleep when he gets like that. I mean I laid down with him in my bed and sang to him and had him asleep but he woke up screaming and WOULD NOT go back to sleep. I about cried when he did that. I wanted to spend time with Brian for a little bit before we went to bed. We have not had the chance to read our scriptures together because he works nights or I fall asleep with Iain while getting Iain down for the night. I just want to spend time with my husband. But on the flip side to him staying up so late was...He slept in his crib for 8 hours and than kinda woke up to eat and than slept for another hour and a half. Amazing, I know. And for the first time for I don't know, Brian and I were able to have our bed all to ourselves. I hope that it happens again tonight.