YOUR MUSCLES FREEZE. A little known fact is that when you dream, the large body muscles, like in your arms and legs, become immobile, as a temporary state of paralysis.
THE DREAMING AND WAKING STATES CAN OVERLAP. Though waking and dreaming are separate states of awareness, their boundaries are not always distinct and there can be a few rare moments of brief overlap. If you accidentally wake up at the end of a dream but are not yet quite awake—which can happen during an intense or scary dream—the effect can be startling. Your mind may still be partly lodged in the dream and yet partially awake. You may notice that you can’t move, an experience people often cite with trepidation. Not being able to move during a dream is normal. The paralysis vanishes when the dream ends or as you fully awaken. This is simply an overlap experience between waking and dreaming.
YOU DO NOT SLEEPWALK WHILE HAVING A DREAM. A common misconception is that people sleepwalk because they are acting out a dream. Not so. Because your arms and legs do not move when dreaming, you cannot physically act out your dreams. People who sleepwalk are not actually dreaming, even though they may report vivid images. Sleepwalking is a type of sleep disorder that most often occurs during deep-sleep, which is stage three, the deepest phase of sleep.
THE BOUNCE-BACK EFFECT. If you lose or reduce your “dream time” for even one night due to a lack of sleep, the next time that you sleep, you will experience extra dreaming time, until you catch up. This bounce-back effect restores the missed dream time, an effect that highlights the importance of dreaming as a built-in, physiological mechanism.