When this is over, the cycle starts over; the original star dies and becomes a white dwarf. White Dwarf The core of a white dwarf star surrounds itself with layers of hydrogen, which still burn, continuing to fuse.
REM sleep is important because it is the restorative part of our sleep cycle. Typically, you begin the sleep cycle with a period of non-REM sleep followed by a very short period of REM sleep. The period of non-REM sleep is made up of stages 1 to 4. Each stage can last from 5 to 15 minutes.
REM is the stage of sleep when you have most of your dreams. It is only about 20% of your total sleep time. Your blood pressure and heart rate can go up and down during this stage. If you have a nightmare that wakes you up, you may find that your heart is racing.