SLEEEEEEP!!!! For the love of God, go to sleep!!!

That's what I've been telling my children, who have been boycotting sleep. We were doing ok in the bedtime department for a while, but then they realized they can actually make veins pop out of mommy's forehead if they refuse to sleep. It's 12:01 CST and I believe they are just now asleep. I say believe because I'm scared to go check. They were up less than 30 minutes ago, and it's been at least 2 hours since I took the lightbulb out so they couldn't turn the light on anymore. Please, I'm begging you fellow bloggers, give me some advice!!! They don't get sweets before bed, they have plenty of exercise and activity during the day, we have a bedtime routine, and there is a night light in there. Here's what happens:
Time for bed, we go through our routine. Shane points at his pillow wanting me to lay down with him, which I do for about 2 minutes. Mads gets upset because I'm giving her brother attention, so I tell Shane good night, kiss him, and go over to Madison. Snuggle her a bit, kiss her, tell them both good night, at which point Shane FREAKS!! 5 minutes of him screaming at the door, I go in and lay him back down. He quiets, then turns on the light until I catch them playing. Repeat for the next hour or so, before I finally take the bulb out. 2 hours of playing and talking to each other in the dark, until Mommy's veins are bulging, and sometime around midnight they fall asleep. Please help.... before I need professional help, or at least medicinal relief!!!