An REM cycle takes about 90 minutes, I think it has something to do with that. I read somewhere that you're supposed to sleep in 90-minute intervals.
I agree. In addition to my nightly 12 hour slumber to maximize muscular and cns recovery from my brutal training sessions and high calorie diet, I find that two 90 minute naps each day further accelerate the anabolic / anticatabolic processes. These muscle snoozes assist greatly with optimizing the body's secretions of gh and testosterone.
I should also add that during the night I get up at least once to drink a protein shake, and I'm thinking that perhaps even that is not enough, despite the fact that I have a shake with slower acting protein right before bed, and a fast acting whey / creatine / high GI carb shake first thing in the morning, about 30-60 minutes before breakfast.
I initially considered getting up every three hours during the night for a shake, but quickly dismissed that - it would start to interfere with sleep and recovery. So I'm in the early stages of developing a sort of portable time released iv device that would keep the body infused with the proper ratios of muscle building nutrients and hormones. Stay anabolic 24/7, and never have to worry about going catabolic again! Anyone want to get in on this with me? $