Sleep is fun, people who regularly lack it will tell you they're "just fine" but they've been lacking sleep for so long that the baseline they're comparing themselves to is already skewed. Take two weeks off, avoid alcohol and other stimulant, avoid artificial light after 8 and wake up without an alarm. You'll see how you feel after that regimen. Your body knows exactly how much sleep it needs. But that's not compati…
I dunno, maybe I’m weird, but without an alarm I can sleep 12 hours. And when I do, I feel like total shit: very tired, groggy, and a little depressed. If I sleep 5-7 hours on the otherhand, I feel much better.
Of course, lying down for a long time will have side effect on your muscles (headaches, groggyness) but I'm sure your body would return to normal sleep patterns after some time.