Even directly under the lamp, 115 from a 150w that's 25" off the ground is waaaay high, so unless you have a thermometer under it, I doubt it's that hot. I am using a 250w bulb that's about ~14" off the ground when they were a week old, with a thermometer directly under it, and I got about 95-100 directly beneath it.
Anyway, their first two-three days are the worrying days. You'll be up all night checking on them, it's normal. As far as sleeping... you need to look for more detail. Are ALL of them sleeping the same amount, or are 1-2 sleeping more than the others? Generally, at that age, when one decides she's hungry, suddenly they ALL decide they're hungry and it's a feeding frenzy. If you have one or two that sleep right through that, then maybe I'd be worried. But when they're all sleeping, also note: is this one breathing harder/softer than the others? (you can tell just by watching their backs rise) Ask yourself, when I put my hand in the cage and make some noise, do they ALL open their eyes and scatter, or do one or two open their eyes and then go back to sleep? Even picking them up (slow and careful!) helps, the two I had that didn't make it from shipping would show signs of life, but quickly go "back to sleep/comatose" shortly after being picked up, while the healthy ones would look at me like "What are you looking at, punk? Put me down this instant!"
Overall, your first week should be a lot like what Krazzy said: run around for 10-20min, fall over (in various, terrifying play-dead positions) and pass out, poop a bit, repeat. Just keep a close eye for chicks not doing what everyone else is doing. This young, I found lethargy the best way to single out a sick chick.
I hope your kids are just stressing you out for no reason! Be sure to post symptoms/pics if one is worrying you, people here are full of great advice!