This muscle atonia or muscle paralysis occurs as a protective means to keep one from acting out their dreams. It may be during this stage that the brain also refreshes itself for new learning the following day. Happy dreaming! Most sleep disorders can be treated effectively. Because REM sleep is the sleep stage at which most dreaming takes place, this paralysis could be nature's way of making sure we don't act out our dreams.
Practicing other aspects of good sleep hygiene — like powering down electronics and nixing the nightcap — may also help improve your sleep —and maybe even your dreams. The brain stem includes structures called the pons, medulla, and midbrain.
One does not go straight from deep sleep to REM sleep, however. Your muscles are relaxed and it may be difficult to awaken you. The fourth stage, REM sleep, is when our breathing rate quickens and our eyes move under our eyelids.
Specialized cells in the retinas of your eyes process light and tell the brain whether it is day or night and can advance or delay our sleep-wake cycle. Also, different genes have been identified with such sleep disorders as familial advanced sleep-phase disorder, narcolepsy, and restless legs syndrome.