Originally Posted by SandySwimmer
I can't site the studies, but I've read that you need the longer sleep to get into REM sleep. They've done studies with mice and those with the shorter bursts had higher levels of cortisone, the stress hormone, even though they were getting the same number of hours of sleep.
Also, athletes often need closer to 9-10 hours of sleep for recovery and to avoid injuries.
yes. there are multiple, dynamic phases of REM sleep that will not be attained without a longer, single bout of restfulness as mentioned above.