I thought I was being too paranoid when my chicks were new. I had them in the brooder for 6-7 weeks and never got over the startle/doubt seeing one passed out. Especially the contorted broken neck positions. Now I wish I'd taken photos and enjoyed it more vs nail biting. I cannot easily sneak up on them in their run so miss the close ups now that they are older, sigh....Oh, no, chicks really DO just fall over asleep all the time. Its one reason why you have to be careful with their waterers, like putting marbles into them, so sleepy chicks dont drown. I learned to tap tap the sides of the brooder when I found them all looking dead; they wake up and my heart starts again.