Our sleep progresses through four distinct cycles, and important upkeep tasks are going on during each one. We start out in light sleep, also called stage 1, when we can be easily awakened. This is followed by stage 2, when it would be slightly more difficult to wake us, and we are transitioning to deep sleep. During stage 3, deep sleep, most of the important cell repair and system restoration is happening. The fourth stage is rapid-eye movement (REM) sleep, when our brains are very active and dreaming takes place. We move through these cycles 4 or 5 times during a full night's sleep.

MAKE SLEEP A PRIORITY VIDEOS

CHAPTER 1 The Importance of Sleep Sleep is not a luxury. It is essential to our fitness, memory, mood and overall health. VIEW VIDEO

CHAPTER 3 (currently viewing) We Sleep in Cycles Our sleep progresses through four distinct cycles, and each plays a role in maintaining our health. VIEW VIDEO

CHAPTER 10 Sleep and Your Weight A good night's sleep keeps two important appetite-control hormones in balance. VIEW VIDEO

CHAPTER 14 Could You Have Sleep Apnea? This breathing disorder disrupts sleep and plays havoc with your health. VIEW VIDEO

CHAPTER 17 Seniors Need Sleep Seniors should still aim for about eight hours of sleep per night. VIEW VIDEO